Apparatus and method for measuring forces in a knee joint

ABSTRACT

An apparatus for measuring forces in a knee joint. The apparatus includes a first transducer configured to be position in a medial compartment of the knee joint. The first transducer is configured to measure a first force in the medial compartment and transmit the first measured force to a display. The apparatus also includes a second transducer configured to be positioned in a lateral compartment of the knee joint. The second transducer is configured to measure a second force in the lateral compartment and transmit the second measured force to the display.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/859,516 filed Apr. 9, 2013; which is a continuation of U.S. patentapplication Ser. No. 10/888,783 filed Jul. 9, 2004; which is acontinuation of Ser. No. 10/191,751 (now U.S. Pat. No. 7,104,996), filedJul. 8, 2002; which is a continuation-in-part of each of the following:U.S. patent application Ser. No. 09/976,396 filed Oct. 11, 2001 (nowU.S. Pat. No. 6,770,078); and U.S. patent application Ser. No.09/941,185 filed Aug. 28, 2001 (now U.S. Pat. No. 6,702,821).

BACKGROUND OF THE INVENTION

The present invention relates to a new and improved method of performingsurgery, and instruments, implants, and other surgical implements thatcan be used in surgery. The surgery may be of any desired type. Thesurgery may be performed on joints in a patient's body. The surgery maybe performed on any desired joint in a patient's body. Regardless of thetype of surgery to be performed, a limited incision may advantageouslybe utilized.

In some embodiments, this specification relates to limited incisionpartial or total knee joint replacements and revisions and is the resultof a continuation of work which was previously performed in conjunctionwith the subject matter of U.S. Pat. No. 5,514,143. This specificationalso contains subject matter which relates to U.S. Pat. Nos. 5,163,949;5,269,785; 5,549,683; 5,662,710; 5,667,520; 5,961,499; 6,059,817; and6,099,531. Although this specification refers to knee joints, it shouldbe understood that the subject matter of this application is alsoapplicable to joints in many different portions of a patient's body, forexample a shoulder, spine, arm, hand, hip or foot of a patient.

During a total or partial knee replacement or revision, an incision ismade in a knee portion of a leg of the patient to obtain access to theknee joint. The incision is relatively long to enable instrumentation,such as a femoral alignment guide, anterior resection guide, distalresection guide, femoral cutting guide, and femoral anterior, posteriorand chamfer resection guide to be positioned relative to a distal endportion of the femur. In addition, the incision must be relatively largeto enable a tibial resection guide to be positioned relative to theproximal end portion of the tibia.

With known procedures of total or partial knee replacement, the incisionin the knee portion of the patient is made with the leg of the patientextended (straight) while the patient is lying on his or her back. Atthis time, the extended leg of the patient is disposed along and restson a patient support surface. After the incision has been made in theknee portion of the leg of the patient, the leg is flexed and a footconnected with the leg moves along the patient support surface. The kneeportion of the flexed leg of the patient is disposed above the patientsupport surface. This results in the soft tissue in the knee beingcompressed against the back of the knee joint. This makes it verydifficult to access posterior soft tissue to remove bone spurs(ostified), meniscus, posterior capsule, ligaments in the back of thejoint, and/or any residual soft tissue or connective tissue that isblocking further flexion.

After the incision has been made and while the leg is flexed with thefoot above the patient support surface, the surgeon cannot viewarteries, nerves and veins which are sitting just posterior to the kneecapsule. Therefore, a surgeon may be very reluctant, or at least verycareful, of inserting instruments into the back of the knee joint toremove tissue. This may result in osteophytes, bone spurs and similartypes of posterior soft tissue being left in place.

With known techniques, the patella is commonly everted from its normalposition. When the patella is everted, the inner side of the patella isexposed and faces outward away from end portions of the femur and tibia.The outer side of the everted patella faces inward toward the endportions of the femur and the tibia. Moving the everted patella to oneside of end portions of the femur and tibia tends to increase the sizeof the incision which must be made in the knee portion of the patient'sleg.

After implants have been positioned in the knee portion of the patient'sleg, it is common to check for flexion and extension balancing ofligaments by flexing and extending the knee portion with the foot abovethe support surface. If the ligaments are too tight medially orlaterally, they can be released to obtain the desired tension. However,the checking of ligament balance by flexing and extending the leg of thepatient, ignores rotational balancing of ligaments. Since the femoralimplant is movable relative to the tibial implant, the stability of theknee joint is dependent upon balancing of the ligaments in flexion,extension, and rotation.

SUMMARY OF THE INVENTION

The present invention relates to a new and improved method and apparatusfor use in performing any desired type of surgery on a joint in apatient's body. The joint may advantageously be a knee joint. However,the method and apparatus may be used in association with surgery onother joints in a patient's body. There are many different features ofthe present invention which may used either together or separately inassociation with many different types of surgery. Although features ofthe present invention may be used with many different surgicalprocedures, the invention is described herein in conjunction withsurgery on a joint in a patient's body.

One of the features of the present invention relates to the making of alimited incision. The limited incision may be in any desired portion ofa patient's body. For example, the limited incision may be in a kneeportion of a leg of a patient. The limited incision may be made while alower portion of the leg of the patient is extending downward from theupper portion of the leg of the patient. At this time, a foot connectedwith the lower portion of the leg of the patient may be below a surfaceon which the patient is supported. The limited incision may be madewhile the lower portion of the leg of the patient is suspended from theupper portion of the leg or while the lower portion of the leg and/orthe foot of the patient are held by a support device. After the incisionhas been made, any one of many surgical procedures may be undertaken.

It is believed that in certain circumstances, it may be desired to havea main incision of limited length and a secondary incision of evensmaller length. The secondary incision may be a portal or stab wound. Acutting tool may be moved through the secondary incision. An implant maybe moved through the main incision.

Once the incision has been made, a patella in a knee portion of thepatient may be offset to one side of its normal position. When thepatella is offset, an inner side of the patella faces inward toward theend portions of a femur and tibia. If desired, the patella can be cutand realigned in situ, with minimal or no subluxation. Additionally, thecutting and/or realignment can be done while the knee is in flexion,which is the natural position, rather than extension.

Although any one of many known surgical procedures may be undertakenthrough the limited incision, down sized instrumentation for use in themaking of cuts in a femur and/or tibia may be moved through or part waythrough the incision. The down sized instrumentation may be smaller thanimplants to be positioned in the knee portion of the patient. The downsized instrumentation may have opposite ends which are spaced apart by adistance which is less than the distance between lateral and medialepicondyles on a femur or tibia in the leg of the patient.

It is contemplated that the down sized instrumentation may have cuttingtool guide surfaces of reduced length. The length of the cutting toolguide surfaces may be less than the length of a cut to be made on abone. A cut on a bone in the patient may be completed using previouslycut surfaces as a guide for the cutting tool.

It is contemplated that at least some, if not all, cuts on a bone may bemade using light or other electromagnetic radiation, such as infraredradiation, directed onto the bone as a guide. The light directed ontothe bone may be in the form of a three dimensional image. The lightdirected onto the bone may be a beam along which a cutting or millingtool is moved into engagement with the bone.

There are several different orders in which cuts may be made on bones inthe knee portion of the leg of the patient. It is believed that it maybe advantageous to make the patellar and tibial cuts before making thefemoral cuts.

There are many different reasons to check ligament balancing in a kneeportion of the leg of a patient. Ligament balancing may be checked whilethe knee portion of the leg of the patient is flexed and the foot of thepatient is below the support surface on which the patient is disposed.Flexion and extension balancing of ligaments may be checked by varyingthe extent of flexion of the knee portion of the leg of the patient. Inaddition, rotational stability of the ligaments may be checked byrotating the lower portion of the leg of the patient about its centralaxis. Balancing of ligaments may also be checked by moving the foot ofthe patient sideways, rotating the lower portion of the leg of thepatient, and/or moving the foot anteriorly or posteriorly.

It is believed that it may be advantageous to utilize an endoscope or asimilar apparatus to examine portions of the patient's body which arespaced from the incision. It is also contemplated that images of theknee portion of the patient's leg may be obtained by using any one ofmany known image generating devices other than an endoscope. The imagesmay be obtained while the patient's leg is stationary or in motion. Theimages may be obtained to assist a surgeon in conducting any desiredtype of surgery.

Balancing of the ligaments in the knee portion of a patient's leg may befacilitated by the positioning of one or more transducers betweentendons, ligaments, and/or bones in the knee portion. One transducer maybe positioned relative to a medial side of a knee joint. Anothertransducer may be positioned relative to a lateral side of the kneejoint. During bending of the knee joint, the output from the transducerswill vary as a function of variations in tension forces in theligaments. This enables the tension forces in ligaments in oppositesides of the knee portion to be compared to facilitate balancing of theligaments.

Patellar tracking may be checked by the positioning of one or moretransducers between the patella and the distal end portion of the femur.If desired, one transducer may be placed between a medial portion of thepatella and the distal end portion of the femur. A second transducer maybe placed between a lateral portion of the patella and the distal endportion of the femur. Output signals from a transducer will vary as afunction of variations in force transmitted between the patella andfemur during bending of the leg.

The articular surface on the patella may be repaired. The defectiveoriginal articular surface on the patella may be removed by cutting thepatella while an inner side of the patella faces toward a distal endportion of a femur. The step of cutting the patella may be performedwhile the patella is disposed in situ and is urged toward the distal endportion of the femur by connective tissue. An implant may then bepositioned on the patella.

It is contemplated that the size of the incision in the knee or otherportion of the patient may be minimized by conducting surgery through acannula. The cannula may be expandable. To facilitate moving of animplant through the cannula, the implant may be formed in two or moreportions. The portions of the implant may be interconnected when theportions of the implant have been positioned in the patient's body.Although the implants disclosed herein are associated with a patient'sknee, it should be understood that the implants may be positioned at anydesired location in a patient's body.

An implant may be positioned in a recess formed in a bone in a patient.The implant may contain biological resurfacing and/or bone growthpromoting materials. The implant may contain mesenchymal cells and/ortissue inductive factors. Alternatively, the implant may be formed ofone or more materials which do not enable bone to grow into the implant.

In accordance with one of the features of the present invention, bodytissue may be moved or stretched by a device which is expandable. Theexpandable device may be biodegradable so that it can be left in apatient's body. The expandable device may be expanded to move and/orstretch body tissue and increase a range of motion of a joint. Theexpandable device may be used to stretch body tissue in which anincision is to be made.

An improved drape system is provided to maintain a sterile field betweena surgeon and a patient during movement of the surgeon relative to thepatient. The improved drape system includes a drape which extendsbetween the surgeon and a drape for the patient. During surgery on aknee portion of a leg of a patient, the drape system extends beneath afoot portion of the leg of a patient. It is contemplated that the drapesystem will be utilized during many different types of operations otherthan surgery on a leg of a patient.

An implant may be movable relative to both a femur and a tibia in a legof a patient during bending of the leg. The implant may include a singlemember which is disposed between and engaged by end portions of both thefemur and tibia. Alternatively, the implant may include a plurality ofmembers which are disposed in engagement with each other. If desired,one of the members of the plurality of members may be secured to a boneand engaged by a member which is not secured to a bone. The implant maybe secured to soft tissue in the knee portion of the patient's leg.

There are many different features to the present invention. It iscontemplated that these features may be used together or separately. Itis also contemplated that the features may be utilized in associationwith joints in a patient's body other than a knee joint. For example,features of the present invention may be used in association withsurgery on vertebral joints or glenoid joints. However, it is believedthat many of the features may be advantageously utilized together duringthe performance of surgery on a patient's knee. However, the inventionshould not be limited to any particular combination of features or tosurgery on any particular joint in a patient's body. It is contemplatedthat features of the present invention will be used in association withsurgery which is not performed on a joint in a patient's body.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of the invention will become moreapparent upon a consideration of the following description taken inconnection with the accompanying drawings wherein:

FIG. 1 is a schematic illustration depicting extended and flexedpositions of a patient's leg during performance of knee surgery in aknown manner;

FIG. 2 is a schematic illustration depicting the manner in which a legsupport is used to support an upper portion of a leg of a patient abovea support surface on which the patient is disposed in a supineorientation during performance of knee surgery;

FIG. 3 is a schematic illustration depicting the patient's leg after aportion of a drape system has been positioned over the patient, the legbeing shown in a flexed condition with the foot below the patientsupport surface and with an upper portion of the leg supported by theleg support of FIG. 2;

FIG. 4 is a schematic illustration of the patient's leg of FIGS. 2 and 3in an extended condition and of the drape system which extends between asurgeon and the patient;

FIG. 5 is a schematic illustration depicting the manner in which thedrape system of FIG. 4 maintains a sterile field during movement of thesurgeon relative to the patient;

FIG. 6 is a schematic illustration depicting the manner in which anincision is made in the knee portion of the leg of the patient when theleg is in the position illustrated in FIGS. 2 and 3;

FIG. 7 is a schematic illustration depicting the manner in which theincision is expanded and a patella is everted with the leg of thepatient extended;

FIG. 8 is a schematic illustration depicting the manner in which a drillis utilized to form a passage in a femur in the upper portion of the legof the patient with the leg in the position illustrated in FIGS. 2 and 3and the patella offset from its normal position;

FIG. 9 is a schematic illustration of the positioning of a femoralalignment guide in the hole formed by the drill of FIG. 8 with the legof the patient in the position illustrated in FIGS. 2 and 3;

FIG. 10 is a schematic illustration depicting the position of ananterior resection guide and a stylus relative to the femoral alignmentguide of FIG. 9 before an anterior femur cut has been made with the legof the patient in the position illustrated in FIGS. 2 and 3;

FIG. 11 is a schematic illustration, taken generally along the line11-11 of FIG. 10, further illustrating the relationship of the anteriorresection guide and stylus to the distal end portion of the femur;

FIG. 12 is a schematic illustration further illustrating therelationship of the anterior resection guide and stylus to the distalend portion of the femur;

FIG. 13 is a schematic illustration depicting the manner in which acutting tool is moved along a guide surface on the anterior resectionguide during making of an anterior femur cut with the leg of the patientin the position illustrated in FIGS. 2 and 3;

FIG. 14 is a schematic illustration depicting the relationship of thefemoral alignment guide to the femur after making of the anterior femurcut of FIG. 13, the anterior resection guide and stylus being removedfrom the femoral alignment guide, and the leg of the patient being inthe position illustrated in FIGS. 2 and 3;

FIG. 15 is a schematic illustration of the anterior femur cut andfemoral alignment guide of FIG. 14;

FIG. 16 is a schematic illustration depicting the manner in which thefemoral alignment guide is utilized to position a distal resection guiderelative to the distal end portion of the femur after making of theanterior femur cut and with the leg of the patient in the positionillustrated in FIGS. 2 and 3;

FIG. 17 is a schematic illustration depicting the manner in which adistal femur cut is made with a cutting tool after the femoral alignmentguide has been removed, the leg of the patient being in the positionillustrated in FIGS. 2 and 3;

FIG. 18 is a schematic illustration depicting the relationship of thecutting tool and distal resection guide of FIG. 17 to the femur;

FIG. 19 is a schematic illustration depicting the manner in which afemoral cutting guide is positioned on the distal end portion of thefemur with the leg of the patient in the position illustrated in FIGS. 2and 3;

FIG. 20 is a schematic illustration further depicting the relationshipof the femoral cutting guide to the distal end portion of the femur;

FIG. 21 is a schematic illustration depicting the relationship of atibial resection guide to the proximal end portion of a tibia in thelower portion of the patient's leg after making the femoral cuts andwith the leg of the patient in the position illustrated in FIGS. 2 and3;

FIG. 22 is a schematic illustration of the distal end portion of thefemur and the proximal end portion of the tibia after making the femoraland tibial cuts with the leg of the patient in the position illustratedin FIGS. 2 and 3 and the patella offset to one side of the incision;

FIG. 23 is a schematic illustration further depicting the femoral andtibial cuts of FIG. 22;

FIG. 24 is a schematic illustration depicting the manner in which forceis applied against the bottom of the patient's foot by a surgeon's kneewith the leg of the patient in the position illustrated in FIGS. 2 and3;

FIG. 25 is a schematic illustration depicting the various directions inwhich the lower portion of the patient's leg can be moved relative tothe upper portion of the patient's leg to expose portions of the bone atthe incision in the knee portion of the patient's leg and to checkligament balancing;

FIG. 26 is a schematic illustration depicting the manner in which atibial punch is positioned relative to a tibial base plate with the legof the patient in the position illustrated in FIGS. 2 and 3;

FIG. 27 is a schematic illustration depicting completed preparation ofthe tibia for a tibial tray implant with the leg of the patient in theposition illustrated in FIGS. 2 and 3;

FIG. 28 is a schematic illustration depicting positioning of a tibialbearing insert in the tibial tray of FIG. 27 with the leg of the patientin the position illustrated in FIGS. 2 and 3;

FIG. 29 is a schematic illustration depicting femoral and tibialimplants with the leg of the patient in the position illustrated inFIGS. 2 and 3;

FIG. 30 is a schematic illustration of an apparatus which may beutilized to move the lower portion of a patient's leg relative to theupper portion of a patient's leg when the patient's kg is in theposition illustrated in FIGS. 2 and 3;

FIG. 31 is a schematic illustration depicting the manner in which adistal resection guide is connected with a patient's femur by pins whichextend through the guide and through skin in the upper portion of thepatient's leg into the femur with the leg of the patient in the positionillustrated in FIGS. 2 and 3;

FIG. 32 is a schematic illustration depicting the manner in which anendoscope may be inserted through an incision in a patient's knee toinspect portions of the patient's knee which are remote from theincision with the leg of the patient in the position illustrated inFIGS. 2 and 3;

FIG. 33 is a schematic illustration similar to FIG. 32, depicting themanner in which the endoscope may be inserted through the incision inthe patient's knee with the leg of the patient extended;

FIG. 34 is a schematic illustration depicting the manner in which animaging apparatus may be utilized to generate images of a portion of thepatient's leg and the manner in which a robot may be utilized toposition cutting tools or other devices relative to the patient's legwith the patient's leg in the position illustrated in FIGS. 2 and 3;

FIG. 35 is a schematic illustration depicting the relationship of a cutline to a patella in a knee of the leg of the patient with the leg inthe position illustrated in FIGS. 2 and 3 and with the patella in thenormal position;

FIG. 36 is a schematic illustration depicting the manner in which acutting tool is moved relative to a guide member to cut the patella ofFIG. 35 while the patella is disposed in situ;

FIG. 37 is a schematic illustration depicting the manner in which atibial alignment shaft and a tibial resection guide are positionedrelative to a tibia in a lower portion of a leg of the patient with theleg of the patient in the position illustrated in FIGS. 2 and 3;

FIG. 38 is an enlarged fragmentary view of a portion of FIG. 37 andillustrating the construction of the tibial resection guide;

FIG. 39 is a schematic illustration depicting the relationship betweenan expandable cannula and an incision in the knee portion of one leg ofthe patient with the leg of the patient in the position illustrated inFIGS. 2 and 3;

FIG. 40 is a schematic illustration depicting the relationship betweentwo separate portions of an implant which are interconnected within thepatient's body;

FIG. 41 is a schematic illustration depicting the relationship oftransducers to a flexed knee joint of a patient when the leg of thepatient is in the position illustrated in FIGS. 2 and 3;

FIG. 42 is a schematic illustration, generally similar to FIG. 41,illustrating the relationship of the transducers to the knee joint whenthe leg of the patient is extended;

FIG. 43 is a schematic illustration of a distal end portion of a femurin a leg of a patient with the leg in the position illustrated in FIGS.2 and 3 and illustrating the relationship of an implant to a recess inthe end portion of the femur;

FIG. 44 is a schematic sectional view depicting the manner in which acutting tool is used to form a recess in the end portion of the femur ofFIG. 43 with the leg of the patient in the position illustrated in FIGS.2 and 3;

FIG. 45 is a schematic sectional view, taken generally along the line45-45 of FIG. 43 further illustrating the relationship of the implant tothe recess;

FIG. 46 is a schematic end view of a proximal end portion of a tibia ina leg of a patient, with the leg in the position illustrated in FIGS. 2and 3, illustrating the relationship of an implant to a recess in theend portion of the tibia;

FIG. 47 is a schematic sectional view depicting the manner in which acutting tool is used to form the recess in the end portion of the tibiaof FIG. 46;

FIG. 48 is a schematic sectional view, taken generally along the line48-48 of FIG. 46, further illustrating the relationship of the implantto the recess;

FIG. 49 is a schematic sectional view illustrating the relationship ofanother implant to a recess in a bone in a patient's body;

FIG. 50 is a schematic illustration depicting the relationship between atibial implant and a tibia in the leg of the patient;

FIG. 51 is a schematic illustration depicting the relationship ofexpandable devices to the knee portion of a patient's leg;

FIG. 52 is a schematic illustration depicting the manner in which anexpandable device may be positioned relative to a knee portion of apatient's leg with the patient's leg in the position illustrated inFIGS. 2 and 3;

FIG. 53 is a schematic illustration depicting the manner in which afemoral cutting guide may be mounted on a distal end of a femur in apatient's leg with the patient's leg in the position illustrated inFIGS. 2 and 3;

FIG. 54 is a schematic illustration of the manner in which a femoralcutting guide may be mounted on a side surface of a femur in a patient'sleg with the patient's leg in the position illustrated in FIGS. 2 and 3;

FIG. 55 is a schematic illustration depicting the manner in which lightis directed onto a distal end portion of a femur with the patient's legin the position illustrated in FIGS. 2 and 3;

FIG. 56 is a schematic illustration depicting the manner in which lightis used to guide movement of a cutting tool relative to a distal endportion of a femur with the patient's leg in the position illustrated inFIGS. 2 and 3;

FIG. 57 is a schematic illustration depicting the manner in which acutting tool is moved relative to a secondary incision with a kneeportion of a patient's leg in the position illustrated in FIGS. 2 and 3;

FIG. 58 is schematic illustration depicting the relationship oftransducers to a patella and distal end portion of a femur with thepatient's leg in the position illustrated in FIGS. 2 and 3;

FIG. 59 is a schematic illustration depicting the relationship between amovable implant, a distal end portion of a femur, and a proximal endportion of a tibia in a knee portion of a leg of a patient;

FIG. 60 is a plan view of a proximal end portion of a tibia depictingthe manner in which an implant may be inlaid into a tibia;

FIG. 61 is a schematic illustration, generally similar to FIG. 59,depicting the relationship between a movable implant formed by aplurality of members, a distal end portion of a femur, and a proximalend portion of a tibia in a knee portion of a leg of a patient;

FIG. 62 is a schematic illustration, generally similar to FIGS. 59 and61, depicting the relationship between an implant formed by a movablemember and a fixed member, a distal end portion of a femur, and aproximal end portion of a tibia in a knee portion of a leg of a patient;

FIG. 63 is a schematic illustration, generally similar to FIG. 59,depicting the manner in which an implant is connected with a ligament ina knee portion of a patient's leg;

FIG. 64 is a schematic illustration, generally similar to FIG. 60,depicting the manner in which an implant is connected with a jointcapsule in a knee portion of a patient's leg;

FIG. 65 is a schematic illustration, generally similar to FIG. 60,depicting the manner in which a retainer holds moldable implant materialin place on a proximal end portion of a tibia in the knee portion of aleg of the patient;

FIG. 66 is a fragmentary sectional view, taken generally along the line66-66 of FIG. 65 further illustrating the manner in which the retainerholds moldable implant material;

FIG. 67 is a schematic illustration depicting the manner in which animplant is provided in a knee portion of a leg of a patient to correctdefects in a joint and in which an osteotomy wedge is provided tocorrect defects in bone alignment;

FIG. 68 is a schematic view of the hip region with a guide wire andcannula inserted;

FIG. 69 is a schematic view of the hip region with an inflatable deviceinserted;

FIG. 70A is a side view of a bone removing instrument according to thepresent invention in a retracted state;

FIG. 70B is a perspective view of the bone removing instrument of FIG.70A in an expanded state;

FIG. 71 is a schematic view of the hip region with the bone remover ofFIG. 70B inserted and removing the femoral head;

FIG. 72 is a schematic view of the hip region with the bone remover ofFIG. 70B inserted and removing the acetabulum;

FIG. 73 is a schematic view of the hip region with a backing of anacetabular component being implanted;

FIG. 74A is a sectional view of one embodiment of a liner for anacetabular component;

FIG. 74B is a sectional view of another embodiment of a liner for anacetabular component;

FIG. 75 is a schematic illustration of a knee joint with an osteotomyperformed;

FIG. 76 is a schematic illustration of the access created by theosteotomy of the knee joint of FIG. 75 with the patella not shown forclarity;

FIG. 77 is a schematic illustration of the knee joint of FIG. 75 withthe osteotomy repaired;

FIG. 78 is an exploded view of a modular tibial component;

FIG. 79 is a schematic illustration of the modular tibial component ofFIG. 78 assembled;

FIG. 80 is a schematic illustration of a tibial component;

FIG. 81 is a schematic illustration of a tibial side-cutting jig for thetibial component of FIG. 80,

FIG. 82 is a front view of a tibial component;

FIG. 83 is a schematic illustration of the tibial component of FIG. 82being implanted;

FIG. 84 is another schematic illustration of the tibial component ofFIG. 82 being implanted;

FIG. 85 is a side view of a patellar implant;

FIG. 86 is a schematic illustration of a femoral component;

FIG. 87 is a section illustration of the femoral component of FIG. 86;

FIG. 88 is a schematic illustration of a knee implant;

FIG. 89 is an exploded perspective illustration of the total kneeimplant of FIG. 88;

FIG. 90 is a schematic illustration of a tibial component of a kneeimplant;

FIG. 91 is a schematic illustration of a bicompartment femoral implant;

FIG. 92 is a schematic illustration of a bicompartment femoral implantand a unilateral tibial implant;

FIG. 93 is a schematic illustration depicting the manner in which anadjustable femoral cutting jig may be mounted on a distal end of a femurin a patient's leg;

FIG. 94 is a schematic illustration of a femoral cutting guide having asingle cutting guide surface;

FIG. 95 is a schematic illustration of the femoral cutting guide of FIG.94 with the cutting guide surface in a different position;

FIG. 96 is a schematic illustration of another embodiment of a femoralcutting guide having a single cutting guide surface;

FIG. 97 is a schematic illustration of an implant having a reducedarticulating surface area;

FIG. 98 is a schematic illustration showing a number of the implants ofFIG. 97 implanted in an acetabulum;

FIG. 99 is a schematic illustration of another implant having a reducedarticulating surface area; and

FIG. 100 is a schematic illustration of another implant having a reducedarticulating surface area.

DESCRIPTION OF SPECIFIC PREFERRED EMBODIMENTS OF THE INVENTION KnownMethod of Performing Surgery on a Patient's Knee

During the performance of surgery using known methods, a patient issupported on an operating table or other support surface 52 (FIG. 1).When a leg 50 of the patient is in the extended position illustrated indashed lines in FIG. 1, a foot 54 connected with a lower portion 56 ofthe leg 50 is disposed above the support surface 52. During an operationon a knee portion 58 of the leg 50, the knee portion is raised andlowered relative to the support surface as the leg 50 is flexed andextended. However, the foot 54 is always disposed above the supportsurface 54 and may be supported by the support surface throughout theoperation.

During this known operating procedure, an incision is made in the kneeportion 58 of the leg 50 when the leg is in the extended positionillustrated in dashed lines in FIG. 1. At this time, the foot 54 of thepatient may rest on the support surface 52 or be disposed in a footsupport located above the support surface. Once an incision has beenformed in the knee portion 58, the leg 50 may be flexed or bent to theposition illustrated in solid lines in FIG. 1.

As the knee portion 58 is bent, the leg 50 is flexed and compresses thesoft tissue of the knee portion 58 against the back of the knee joint.This makes it very difficult to access the posterior of the knee portion58 to remove bone spurs (osteophytes), the meniscus, the posteriorcapsule, and/or any residual soft tissue or bone that is blockingfurther flexion. The catching or pinching of soft tissue in theposterior aspect of the knee portion 58 may prevent further flexion andlimits the range of motion. In addition, arteries, nerves and veins aresitting just posterior of the knee joint.

Due to the lack of access to the posterior of the knee portion 58, asurgeon may be very reluctant or, at least, very careful about insertinginstruments blindly into the back of the knee joint to remove tissue.This may result in osteophytes, bone spurs and similar types ofposterior soft tissue being left in place.

Cuts are made on a femur and tibia with the leg 50 in the bent or flexedcondition, illustrated in FIG. 1. This results in the distal end portionof the femur and the proximal end portion of the tibia in the leg 50being pressed together adjacent to the cuts. This interferes withligament balancing. The relatively large incision which is necessary toaccommodate known instrumentation systems increases time required forthe patient to recover from the operation.

Preparation for Operation

It is contemplated that various features and/or combinations of featuresof the present invention will be utilized during surgery on differentportions of a patient's body, such as a head, trunk or limbs of apatient. Although at least some of the features of the present inventionare believed particularly advantageous when utilized in association withsurgery on any one of the many joints in a patient's body, it isbelieved that the various features and/or combination of the features ofthe present invention are particularly advantageous when utilized inconjunction with surgery on a knee portion of a leg of a patient. Itshould be understood that the various features of the present inventionmay be use separately or in any desired combination of features.

Surgery on the knee portion of the patient may relate to any one of manydifferent aspects of the knee portion, such as ligaments, tendons,articular surfaces, and/or total or partial knee replacements orrevisions. Although the disclosure herein frequently refers to oneparticular type of knee operation, that is, a total knee replacement,features of the invention may be utilized with any desired type ofsurgery. It is believed that it will be apparent to a person having aknowledge of knee surgery how various features of the invention may beutilized with either a full or partial knee replacement. Therefore,there has been only minimal mention herein of how the features of theinvention are applicable to partial knee replacements.

When knee surgery is to be performed in accordance with one of thefeatures of the present invention, the patient 62 (FIG. 2) is disposedon a support surface 64 of an operating table 66. If desired, a patientsupport surface 64 other than an operating table could be used tosupport the patient. A lower portion 68 of a leg 70 extends downwardfrom an upper portion 72 of the leg 70. A foot 74 connected with thelower portion 68 of the leg 70 is disposed below the support surface 64.The leg 70 is flexed so that a knee portion 76 of the leg is bent.

In accordance with another of the features of the present invention, theupper portion 72 of the leg 70 can be supported above the supportsurface 64 by a leg support 80 (FIG. 2). The leg support 80 includes astand or base section 82 which is connected with the operating table 66.The leg support 80 includes a base 84 which is connected with an upperend portion of the stand 82. The base 84 is engaged by and supports theupper portion 72 of the leg 70.

A generally annular thigh holder 86 extends around the upper portion 72of the leg 70 of the patient and is connected with the base 84 and stand82. The base 84 has a portion which extends along the posterior side ofthe upper portion 72 of the leg 70 of the patient. The base 84 supportsthe upper portion 72 of the leg 70 above and spaced from the supportsurface 64. However, the upper portion 72 of the leg 70 could bedisposed in engagement with the support surface 64 if desired.

The leg support 80 supports the leg 70 of the patient with a hip 88 ofthe patient hyperflexed at an angle of twenty to thirty degreesthroughout the operation on the knee portion 76. The leg support 80 mayhave a known commercial construction or may have a construction similarto that disclosed in U.S. Pat. No. 4,373,709 or U.S. Pat. No. 6,012,456.If desired, a tourniquet may be combined with the leg support 80 in amanner similar to that provided in known leg supports or in a marinersimilar to that disclosed in U.S. Pat. No. 4,457,302.

In accordance with another feature of the invention, the lower portion68 (FIG. 3) of the leg 70 is suspended from the upper portion 72 of theleg. This enables the foot 74 and ankle portion 86 of the leg 70 of thepatient to be freely moved in any direction or a combination ofdirections. Thus, the foot 74 and ankle portion 86 of the leg 70 of thepatient can be moved anteriorly or upward (as viewed in FIG. 3) todecrease the extent of flexion of the knee portion 72 or even to extendor straighten the leg 70.

Alternatively, the foot 74 and ankle portion 86 may be moved posteriorlytoward the operating table 66, from the position illustrated in FIG. 3,to hyperflex the knee portion 72 of the leg of a patient. The foot 74may be moved sidewardly, that is in either a lateral or medialdirection. In addition, the foot 74 may be rotated about thelongitudinal central axis of the lower portion 68 of the leg 70.

It is contemplated that the foot 74 and ankle portion 86 may besimultaneously moved in a plurality of the directions previouslymentioned. If desired, the upper portion 72 of the leg 70 of the patientmay be supported on a separate section of the operating table 66, in amanner similar to the disclosure in U.S. Pat. No. 5,007,912.

After a drape 90 has been positioned over the patient 62 and theoperating table 66, in the manner illustrated in FIG. 3, the leg 70extends out of the drape. The drape 90 may be connected with the legsupport 80 and have an opening 92 (FIGS. 3 and 4) through which the legof the patient extends. This enables the leg 70 of a patient to be movedbetween the extended position illustrated in FIG. 4 and a hyperflexedposition in which the foot 74 is disposed posteriorly from the positionillustrated in FIG. 3.

When the leg 70 is in a hyperflexed condition, the included anglebetween the upper and lower portions 72 and 68 of the leg 70 is lessthan ninety degrees. The leg 70 may be flexed from the extended positionof FIG. 4 to a hyperflexed position by manually moving the foot 74 andan ankle portion 96 of the leg 70 relative to the operating table 66(FIG. 2) while the upper portion 72 of the leg is held by the legsupport 80. When the leg 70 is hyperflexed, a portion of the foot 74 maybe disposed beneath the operating table 66 (FIG. 2).

An improved drapery system 100 (FIG. 4) includes the drape 90 and adrape 102 connected with a gown 104 on a surgeon 106. The illustrateddrape 102 is formed separately from the drape 90 and gown 104. However,the drape 102 may be integrally formed as one piece with the drape 90.Alternatively, the drape 102 may be integrally formed as one piece withthe gown 104. If formed integral, drape 90, drape 102, and/or gown 104can be provided with a quick release mechanism, such as serrated edges,to allow surgeon 106 to rapidly tear away. Thus, drapery system 100allows the patient to be a sterile field directly or modularly attachedto the surgeon and/or an assistant.

Regardless of whether separate or integral, drape 90 and/or drape 102can include attachments for surgical instruments such as suction, Bovie,arthroscopic equipment, etc. Drape 102 can have a large pouch to collectall fluid, body parts, blood, etc. so they do not drain all over thefloor and are collected in an easily disposable fashion. In this regard,drape 102 can include a drain, with or without active suction, to removefluid and other debris.

Drape 90 could be adhesive drape with a Betadine adhesive or a clearplastic adhesive, either with or without antimicrobial agentsimpregnated, which covers the skin surrounding the operative field.Drape 90 could be a two layer drape with a larger drape below whichsticks to the patient or is loosely attached to the patient and anarrower surgical field drape above for two layer draping.

In the embodiment illustrated in FIG. 4, the drape 102 is formedseparately from the gown 104 and the drape 90. The drape 102 isconnected to the drape 90 by suitable clamps 108. The drape 102 isconnected with the waist of the surgeon 106 by clamps 110 to the gown104. Rather than utilizing clamps 108 to interconnect the drapes 90 and102, the drapes could be interconnected by VELCRO, ties, or other knowndevices. Of course, similar devices could be utilized to connect thedrape 102 with the gown 104 of the surgeon 106. The connection mechanismcan be chosen such that, if surgeon 106 needs to change position withrespect to the patient, the connection mechanism allows re-attachment ofgown 104 to various locations of drape 102.

The improved drapery system 100 maintains a sterile field between theleg 70 and the surgeon 106 during movement of the surgeon relative tothe patient 62. Thus, when the surgeon is in a seated position (FIG. 4)the drapery system 100 provides a sterile field which extends from thesurgeon to the space beneath and adjacent to the leg 70. When thesurgeon stands (FIG. 5) the drapery system 100 continues to maintain asterile field between the surgeon and the patient. This enables thesurgeon 106 to move the leg 70 of a patient during an operation withoutcontaminating the sterile field. The draping system 100 enables thesterile field to be maintained when the patient's leg is moved betweenthe extended position of FIGS. 4 and 5 and a hyperflexed position inwhich the foot 74 of the patient is disposed beneath the operating table66.

During movement of the surgeon 106 relative to the patient, for example,between the seated position of FIG. 4 and the standing position of FIG.5, the drape 102 moves with the surgeon and maintains a sterile field.Thus, when the surgeon 106 moves toward and away from the patient, theend portion of the drape 102 connected with the surgeon also movestoward and away from the patient. As the surgeon moves toward thepatient, a portion of the drape 102 between the surgeon 106 and patientis lowered. As the surgeon moves away from the patient, the portion ofthe drape 102 between the surgeon and patient is raised. The foot 74connected with the leg 70 of the patient is always above the drape 102during movement of the surgeon 106.

Drape 102 and/or drape 90 has flexibility and could be provided withflexed sections or may have a large redundant area which would go downto the surgeon's knees or to the floor to maintain the sterile field. Bytypical sterile technique, anything below the waist level of the surgeonor the support surface is considered un-sterile. However, with draperysystem 100, if drape 102 happens to drop down to the floor, it creates acontiguous sterile field and therefore, the surgeon could retrievedropped objects from the floor if it is contained within drape 102 ordrape 90. This could save a significant amount of money by eliminatingthe need to dispose of (or re-sterilize) fallen surgical instruments orimplants.

Although the drapery system 100 has been illustrated in FIGS. 3-5 inassociation with a patient's leg 70, the drapery system may be used inassociation with surgery on any desired portion of a patient's body. Forexample, the drapery system 100 could be used to maintain a sterilefield between a surgeon and patient during surgery on a trunk portion ofa patient's body. Alternatively, the drapery system 100 could be used tomaintain a sterile field during surgery on a head or arm portion of apatient's body.

Drapery system 100 can use disposable drapes or can be re-sterilizable,either in its entirety or portions thereof. Additionally, known currentdrape technology can be incorporated into drapery system 100. Thisincludes the use of disposable independent drapes, ¾ sheet, disposableadherent drapes, U-drapes, disposable adhesive drapes, Betadine drapes,VELCRO attached drapes, snap, plastic snap drapes, single piece drapes,multi-drapes, two layer drapes, clear plastic drapes, independent orattached to drapes, one piece drapes with stretchable segment forextremities, arthroscopic drapes, shoulder drapes which incorporateU-drapes, square drapes, etc.

In another embodiment, drapes 90, 102 could be configured to create amobile field.

Specifically, the drapes can be made to have a surgeon's helmet attachedto it and part of gown 104 attached to it so that the surgeon wouldliterally walk into the drape system, his hands and his face would gointo the drape to create a mobile surgical field attached to the patientto create even more of a sterile field. The drapery system could havelaminar flow system connected to it to create sterile air coming in andthen a suction coming out so it could have unidirectional airflow tofurther sterilize the field.

The drape system could have a tent, a cover over the top of this tocreate a mobile surgical field so that this could be done in emergencysetting such as a military field or otherwise outdoors. Because thedrape system can be provided with an attachment for flowing air in andout, maintaining extremely sterile air, the drape system could also beused for organ or tissue harvesting, such as bone harvesting under anemergency situation. The drape system could have the surgeon's gown,face mask, sterilizable hood all attached as part of it. It could beunrolled as one sterile pack adhering to the patient and rolling outwardand the surgeon simply walks into the drape as does the assistant. Whenthe procedure is complete, simply roll up the drape and throw it away,thereby maintaining all potential biohazards.

The drape could have a sterile flap where instruments could be passedthrough and/or a simple opening where the assistant could deliverinstruments required through this field or the drape could be a flatopen sheet where the assistant could bring the instruments on top of thesterile surgical field. There also may be a separate attachment for thecirculating nurse.

As previously noted, drape 90 and/or drape 102 may also include anabbreviated gown 104 simply with the arms, front portion of the gown.This abbreviated gown could be a portion of drape 90, 102 so the drapingsystem need not extend fully down to the floor. Rather, the abbreviatedgown would have arm holes so that the surgeon can put his arms throughthe holes and the nurse would put gloves on him once they aresterilized. A provision can be made so that at least one person has anindependently moveable surgical gown.

Incision

In accordance with another feature of the present invention, a limitedincision 114 (FIG. 6) is formed in the knee portion 76 of the leg 70.The incision 114 is made just medial to the patella 120. However, theincision 114 could be disposed laterally of the patella 120. Althoughthe length of the incision 114 may vary depending upon thecircumstances, the incision 114 will usually have a length of betweenabout seven (7) and about thirteen (13) centimeters. However, evensmaller incisions may be made when circumstances permit.

In one embodiment, the incision is made when the knee portion 76 of theleg is flexed and the lower portion 68 of the leg extends downward fromthe upper portion 72 of the leg in the manner illustrated in FIGS. 2 and3. At this time, the upper portion 72 of the leg 70 is supported abovethe support surface 64 by the leg support 80 (FIG. 2). The lower portion68 of the leg 70 is suspended from the upper portion 72 of the leg(FIGS. 2 and 3).

When the knee portion 76 of the leg 70 is flexed so that the lowerportion 68 of the leg is suspended at an angle of approximately ninetydegrees relative to the upper portion 72 (FIGS. 2 and 3), the incision114 (FIG. 6) may have a length of approximately ten (10) centimeters.When the leg 70 is straightened from the flexed condition of FIGS. 2 and3 to the extended condition of FIGS. 4 and 5, the length of the incision114 may decrease by between ten and thirty percent. Thus, in onespecific instance, an incision 114 had a length of approximately eleven(11) centimeters when the leg 70 was in the flexed condition of FIGS. 2,3 and 6 and a length of slightly less than ten (10) centimeters when theleg was in the extended condition of FIG. 5. By making the incision 114with the leg in a flexed condition (FIGS. 2, 3, and 6) and operating onthe leg 70 with the leg in a flexed condition, the overall length of theincision can be reduced from the length of incisions which havepreviously been made in the leg when it is in the extended condition.

The benefits of having a smaller incision include improved cosmeticresults, improved rehab, less dissection of muscle and soft tissue, andpreservation of the quadriceps mechanism.

It is preferred to have the incision 114 located adjacent to the medialedge of the patella 120, in the manner illustrated schematically in FIG.6. However, the incision 114 could be located adjacent to the lateraledge of the patella 120 if desired. Alternatively, the incision 114could be disposed midway between lateral and medial edges of the patella120. By moving the incision 114 laterally or medially away from themidline of the knee, less stress is placed on incision 114 compared to amidline incision.

Although it is desired to minimize the length of the incision 114, it iscontemplated that the incision may have a length of approximately twicethe length of the patella. It may be desired to have the incision 114extend from a proximal end of the tibia in the leg 70 to the epicondylarnotch on the distal end portion of the femur in the leg 70. The lengthand location of the incision 114 may vary depending on the size of theimplants to be positioned in the knee portion 76 and the location atwhich the implants are to be positioned. It is believed that it may bedesired to have the incision 114 be smaller than the implants eventhough the implants must move through the incision. The viscoelasticnature of the body tissue and mobility of the incision 114 enables theimplants to be larger than the incision and still move through theincision.

A straight incision 114 has been illustrated in FIG. 6. However, theincision 114 could have a different configuration if desired. Forexample, the incision 114 could have an L-shaped configuration. Theincision 114 could be skewed at an acute angle to a longitudinal centralaxis of the patella 120. If desired, the incision 114 could have aconfiguration matching the configuration of either the lateral or medialedge of the patella 120.

Immediately after the incision 114 is formed, the leg 70 may be movedfrom the flexed condition of FIGS. 2 and 3 to the extended condition ofFIG. 5. While the leg 70 is in the extended condition, the incision 114(FIG. 7) is elastically expanded using suitable retractors. The incision114 can also be expanded while the leg is in the flexed condition. Theretractors apply force against the viscoelastic body tissue of the kneeportion 76. The retractors have a construction similar to that disclosedin U.S. Pat. No. 5,308,349. Alternatively, a pneumatic retractor, suchas is disclosed in U.S. patent application Ser. No. 09/526,949 filed onMar. 16, 2000 by Peter M. Bonutti may be utilized to expand theincision.

After the incision 114 has been elastically expanded, a patella 120 andtissue on the lateral side of the incision may be everted in a mannerillustrated in FIG. 7. Thus, the patella 120 is moved from the normalorientation of FIG. 6 to the everted or flipped orientation of FIG. 7,preferably while the leg 70 of the patient is in the extendedorientation of FIG. 7. At this time, the inner side 122 of the patella120 is facing outward away from other bones in the knee portion 76. Theouter side of the everted patella 120 is facing inward toward otherbones in the knee portion 76. This enables the inner side 122 of thepatella 120 to be examined.

In order to enable a relatively small incision 114 to be used foroperating on bones in the knee portion 76 of the leg 70 of the patient,the patella 120 is returned back to its normal position with the innerside 122 of the patella facing inward and the outer side of the patellafacing outward. As this occurs, the opening at the incision 114contracts. The retractors are then utilized to apply force againstopposite sides of the incision 114. As this occurs, the viscoelasticbody tissue is extended, the opening at the incision 114 is againexpanded, and the patella 120 is pushed to the lateral side of the kneeportion 76. This moves the patella 120 to a location offset to one sideof the incision 114 in a manner illustrated in FIG. 8. The leg 70 isthen flexed to the orientation shown in FIGS. 2 and 3.

If desired, the foregoing step of inverting the patella 120 may beomitted. The patella 120 may be left in orientations in which the innerside 122 of the patella faces inward throughout the operation. If thisis done, the inner side 122 of the patella 120 may be inspected bytilting the patella from its normal orientation and/or using viewingdevices, such as an endoscope. Regardless of how the inner side 122 ofthe patella 120 is inspected, moving the patella to the offset positionof FIG. 8, with the inner side 122 facing inward, facilitatesutilization of an incision 114 having a limited length. It iscontemplated that many different surgical procedures could be conductedon the knee portion 76 with the patella 120 in the offset position ofFIG. 8. Furthermore, avoiding eversion of the patella 120 significantlyreduces stress on the quadriceps/tendon complex. Applicant has foundthat the stress on the complex is at least 20% less compared to aprocedure with eversion, thereby decreasing the risks of tearing,damage, and strain.

As shown in FIG. 8, a retractor 121 can be used to offset patella 120and/or maintain patella 120 in the offset position. In an exemplaryembodiment, retractor 121 is approximately 2-3 mm thick. Retractor 121also holds soft tissue away to expose the bone. Accordingly, retractor121 can include at least one hole 123 for receiving a pin 125 to secureretractor 121 to bone or other body tissue. Alternatively, a suture orwire can be threaded through hole 123 to secure retractor 121 to tissue.In another embodiment, retractor 121 includes a sharp end to holdretractor 121 to the tissue.

Retractor 121 can be made out of any suitable material, such as metallicmaterials typically used for surgical instruments. If retractor 121 ismade of a polymer, it is contemplated that retractor 121 could bedisposable. If this is done, retractor 121 may be partially or entirelyformed of relatively inexpensive polymeric materials. As previouslydisclosed, the disposable retractors could be sharpened at one end likea Homan. Such a disposable retractor could be made of a polymer such aspolyethylene, which may be malleable to a degree. Thus, the disposableretractor could be deformed to a desired shape to expose the joint asrequired and possibly pin the tissue directly through the malleableportion of the retractor to hold the soft tissue out of the way whileone is working on the bone. This would allow enhanced exposure through asmaller incision, visualizing it through flexion and extension.

The retractors could also be a composite with some metal and someplastic with a portion of the device, flexible, malleable and lockinginto bone to keep the tissue out of the way while one is working on thebone. Additionally, it is contemplated that the retractors could also beheated and malleable intraoperatively. The retractors could be made of abiodegradable material and be left in position to maintain a soft tissuesleeve or exposure so as to minimize scarring the joint. Regardless ofthe material, the retractors could have ribs or a roughened surface togrip the tissue. The retractors could also be coupled with a balloonretractor (discussed below).

Femoral Procedure

Expansion of the incision 114 with the retractors exposes a distal endportion 124 (FIG. 8) of a femur 126 in the upper portion 72 of the leg70. The incision 114 is movable relative to the distal end portion 124of the femur 126 to maximize exposure of the femur through the limitedlength of the incision. The femur 126 is then cut to receive an implant.Although either intramedullary or extramedullary instrumentation can beutilized, intramedullary instrumentation is used in an exemplaryembodiment during cutting of the femur 126. Therefore, a drill 128 isutilized to access the intramedullary canal or marrow cavity in thefemur 126.

The drill 128 is utilized to form a hole 130 in the center of theintercondylar notch in the distal end portion 124 of the femur 126 in aknown manner. The drill 128 is used to form the hole 130 while the leg70 is in the orientation illustrated in FIGS. 2 and 3. The patella 120is in the offset position illustrated in FIG. 8. At this time, the innerside 122 (FIG. 7) of the patella faces toward the femur 126.

An epicondylar reference guide (not shown) engages the hole in thedistal end portion 124 of the femur 126 to enable a line parallel to anepicondylar axis peaks of the medial and lateral condyles to beinscribed on the distal end portion 124 of the femur 126. At this time,the leg 70 is in the orientation illustrated in FIGS. 2, 3, 8 and 9. Ashaft 132 (FIGS. 9, 10, 11 and 12) of a femoral alignment guide 134 isthen inserted into the intermedullary opening 130.

The femoral alignment guide 134 is then aligned with the epicondylarline which extends parallel to the epicondylar axis through the peaks ofthe lateral and medial condyles on the distal end portion 124 of thefemur 126. The femoral alignment guide 134 is utilized to support ananterior resection guide 138 and stylus 140 (FIGS. 10, 11 and 12) on thedistal end portion 124 of the femur 126 in the upper portion 72 of theleg 70 of the patient. Although only the femur 126 is illustrated inFIGS. 10, 11 and 12, it should be understood that the leg 70 is in theorientation illustrated in FIGS. 2 and 3. The upper portion 72 of theleg 70 is supported by the leg support 80.

In accordance with one of the features of the present invention, theinstrumentation is down sized to enable the size of the incision 114(FIG. 9) to be minimized. The downsized instrumentation has a transversedimension which is smaller than a transverse dimension of an implant tobe placed in the knee portion 76 (FIG. 9). Thus, the femoral alignmentguide 134 and anterior resection guide 138 have transverse dimensions,perpendicular to a longitudinal central axis of the femur 126, which aresmaller than transverse dimensions of a femoral implant 290, tibialbearing insert 294, and a tibial tray 286 (FIG. 29) in a directionperpendicular to the longitudinal central axis of the femur 126 (FIG.9).

The instrumentation extends from a center portion of the femur 126toward one side of the femur (FIG. 11). In the particular operationillustrated schematically in FIGS. 7-12, the incision 114 is offset tothe medial side of the patella 120. Therefore, the instrumentation isoffset to the medial side of the femur 126. However, if the incision 114were offset to the lateral side of the patella 120, the instrumentationwould be offset to the lateral side of the femur 126. If the incision114 were centrally disposed relative to the femur 126, theinstrumentation would be centrally disposed relative to the femur. Thus,the instrumentation is in general alignment with the incision 114 andextends only part way across the distal end portion 124 of the femur126.

The femoral alignment guide 134 (FIGS. 10, 11 and 12) and anteriorresection guide 138 have opposite ends which are spaced apart bydistance which is less than a distance between epicondyles 148 and 150on the distal end portion 124 of the femur 126. The distance betweenopposite ends 154 and 156 of the femoral alignment guide 134 is lessthan two thirds (⅔) of the distance between tips 144 and 146 of thelateral and medial epicondyles 148 and 150. Similarly, a distancebetween an end 160 and an opposite end 162 of the anterior resectionguide 138 is less than two thirds (⅔) of the distance between the tips144 and 146 of the lateral and medial epicondyles 148 and 150.

The distance between opposite ends of a known femoral alignment guideand the distance between opposite ends of a known anterior resectionguide are approximately the same as or greater than the distance betweenthe tips 144 and 146 of the lateral and medial condyles 148 and 150. Thedistance between opposite ends of the known femoral alignment guide andthe distance between opposite ends of the known anterior resection guideare greater than the transverse dimensions of the femoral and tibialimplants 286, 290 and 294 (FIG. 29). This known anterior resection guideand femoral alignment guide are commercially available from HowmedicaOsteonics of 359 Veterans Boulevard, Rutherford, N.J. under thedesignation “Scorpio” (trademark) Single Axis Total Knee System.

The incision 114 must be large enough to enable the femoral alignmentguide 134 and the anterior resection guide 138 to pass through theincision. By reducing the size of the femoral alignment guide 134 andanterior resection guide 138, the size of the incision 114 can bereduced. Of course, reducing the size of the incision 118 reduces damageto body tissue of the patient 62. The femoral alignment guide 134 andthe anterior resection guide 138 may be larger than the incision 114.This is because the incision 114 can be resiliently stretched and/ormoved relative to the femur 126 to enable the femoral alignment guide134 and anterior resection guide 138 to move through the incision.

The distance between opposite ends 154 and 156 of the femoral alignmentguide 134 is less than the distance which a femoral implant extendsacross the distal end portion 124 of the femur 126. Similarly, thedistance between opposite ends 160 and 162 of the anterior resectionguide 138 is less than the distance which the femoral implant extendsacross the distal end portion 124 of the femur 126. The femoralalignment guide 134 and the anterior resection guide 138 both extendmedially from a center portion of the femur 126. However, if theincision 114 were offset laterally of the patella 120, the femoralalignment guide 134 and the anterior resection guide 138 would extendlaterally from the center portion of the femur 126. Similarly, if theincision 114 was centered relative to the patella 120, the femoralalignment guide 134 and anterior resection guide 138 would be centeredrelative to the femur 126.

If leg 70 is positioned as shown in FIGS. 2 and 3, positioning of thefemoral alignment guide 134 and anterior resection guide 138 on thedistal end portion 124 of the femur 126 is facilitated by distractingthe knee joint under the influence of the weight of the lower portion 68of the patient's leg and the foot 74. Thus, when the femoral alignmentguide 134 and anterior resection guide 138 are positioned on the distalend portion 124 of the femur 126, the lower portion 68 of the leg 70 canbe suspended from the upper portion 72 of the leg. At this time, thefoot 74 is below the level of the support surface 64 (FIG. 2) on whichthe patient is disposed in a supine orientation. The upper portion 72 ofthe patient's leg 70 is supported above the support surface 64 by theleg support 80 (FIG. 2).

By distracting the knee joint under the influence of the weight of thelower portion 68 of the leg of the patient, the distal end portion 124of the femur 126 is exposed through the relatively small incision 114(FIG. 9). Exposure of the distal end portion 124 of the femur 126 at thelimited incision 114 is promoted by moving the lower portion 68 of theleg 70 and the incision relative to the femur. In addition, exposure ofthe distal end portion 124 of the femur 126 is promoted by having thepatella 120 offset to the lateral side of its normal position. The innerside 122 of the patella 120 faces inward toward the distal end portion124 of the femur 126 so that the skin on the knee portion 76 is notexcessively stretched by everting the patella.

In accordance with another feature of the present invention, theinstrumentation is at least partially positioned between the distal endportion 124 of the femur 126 and body tissue of the knee portion 76(FIG. 9). To enable the size of the incision 114 to be minimized, theinstrumentation is moved laterally of the incision so that a portion ofthe instrumentation moves between the knee capsule and the end portion124 of the femur 126. This results in a portion of the instrumentationbeing exposed at the incision 114 and a laterally extending portion ofthe instrumentation being concealed by body tissue. For example, the end154 (FIG. 11) of the femoral alignment guide 134 and/or the end 160 ofthe anterior resection guide 138 are overlaid by body tissue adjacent tothe lateral edge portion of the incision 114. The body tissue whichoverlies portions of the instrumentation may include skin, the kneecapsule, and connective and soft tissues.

With prior art instrumentation, the soft tissue must be completelydissected so that the distal end portion 124 of the femur 126 is fullyexposed. In contrast, the instrumentation of the present invention canbe at least partially positioned between the distal end portion 124 ofthe femur 126 and body tissue of the knee portion 76 (FIG. 9). Asdiscussed in more detail below, the soft tissue can be lifted orotherwise retracted. This minimizes the need for dissection.

When the femoral alignment guide 134 and anterior resection guide 138are connected with the femur 126, central axis of the femoral alignmentguide and anterior resection guide are medially offset from the centralaxis of the femur. Thus, the central axis of the femur 216 extendsthrough a lateral portion, that is, left portion as viewed in FIG. 11,of the femoral alignment guide 134. The anterior resection guide 138 isalmost entirely offset to the right (as viewed in FIG. 11) of thecentral axis of the femur 126. The incision 114 is disposed along amedial edge, that is, a right edge as viewed in FIG. 6, of the patella120 when the patella is in its normal or initial position.

By having both the incision 114 and the instrumentation medially offsetrelative to the femur 126, the central portion of the instrumentation isexposed at the incision. Thus, the medial edge of the incision overlapsthe medial end 156 of the femoral alignment guide 134 and the medial end162 of the anterior resection guide 138. Similarly, the lateral edge ofthe incision 114 overlaps the lateral end 154 of the femoral alignmentguide 134 and the lateral end 160 of the anterior resection guide 138.

In view of the foregoing, it can be seen that the leg 70 (FIG. 3) of thepatient 62 (FIG. 2) is maintained in the position illustrated in FIGS. 2and 3 with the foot 74 of the patient below the support surface 64 uponwhich the patient is supported in a supine position during forming ofthe incision 114 in the knee portion 76 of the leg 70. The upper portion72 of the patient's leg 70 is supported above the support surface 64 bythe leg support 80 (FIG. 2). In addition, the leg of the patient ismaintained in the position illustrated in FIGS. 2 and 3 duringconnection of the femoral alignment guide 134 and anterior resectionguide 138 with the distal end portion 124 of the femur 126.

Once the femoral alignment guide 134 and anterior resection guide 138have been mounted on the distal end portion 124 of the femur 126, ananterior cut is made in the manner illustrated in FIG. 13, During theanterior cut, a blade 170 of a saw 172 is utilized to make a cut acrossanterior portions of the lateral and medial condyles. The saw blade 170is moved along guide surface 178 (FIGS. 11 and 12) on the anteriorresection guide 138.

The guide surface 178 extends only part way across of the end portion124 of the femur 126 (FIGS. 11 and 13). The guide surface 178 does notextend across the lateral portion of the end portion 124 of the femur126. This at least partially results from the fact that the incision 114(FIG. 6) is offset in a medial direction from the center of the kneeportion 76. The incision 114 extends along the medial edge portion ofthe patella 120 when the patella is in its normal, that is, initial,position. In addition, the large majority of the anterior resectionguide 138 extends medially from the central axis of the shaft 132 of thefemoral alignment guide 134 (FIG. 11). By having the anterior resectionguide disposed in an overlying relationship with the medial portion ofthe end portion 124 of the femur 126 (FIGS. 11 and 13), the size of theincision 114 can be reduced.

When anterior portions of the lateral and medial condyles 148 and 150(FIGS. 10, 11 and 12) on the distal end portion 124 of the femur 126 areto be cut with the saw 172, the blade 170 is pivoted sideways (FIG. 13)so that the cutting end of the blade has an arcuate component ofmovement. The cutting end of the blade 170 will move along a straightpath during part of the movement of the blade along the guide surface178. However, when the blade 170 reaches the ends of the guide surface178, the saw 172 is pivoted to pivot the blade and move the cutting endof the blade along a path having an arcuate configuration. This resultsin a generally fan shaped cut which extends only part way across theanterior side of the lateral and medial condyles on the end portion 124of the femur.

The saw blade may have teeth along opposite longitudinally extendingedges. The saw blade 170 and saw 172 are of the oscillating type.However, a reciprocating type saw and blade may be utilized if desired.Additionally and as later described, a milling device and associatedguides can be used.

Due to the limited length of the anterior resection guide 138, the sawblade 170 is moved along the guide surface 178 to only partiallycomplete the anterior skim cut on the end portion 124 of the femur 126.The guide surface 178 is offset to the medial side of the central axisof femur 126 (FIG. 11). Therefore, the saw blade can only partially formthe lateral portion of the anterior skim cut while the saw blade engagesthe guide surface 178. The anterior resection guide 138 can thendisconnected from the femoral alignment guide 134 (FIGS. 14 and 15) andthe anterior femur cut is completed.

During completion of the anterior femur (skim) cut, previously cutsurfaces on the end portion 124 of the femur 126 can be used to guidethe saw blade 170 (FIG. 13). Thus, an initial portion of the anteriorskim cut is made on the distal end portion 124 of the femur 126 whilethe saw blade 170 is moved along one or more guide surfaces on theanterior resection guide 138. After the anterior resection guide 138 hasbeen disconnected from the femoral alignment guide 134, the saw blade170 is positioned in engagement with the cut surfaces on the distal endportion 124 of the femur 126. This is accomplished by inserting the sawblade 170 into a slot or saw kerf formed in the distal end portion 124of the femur during the initial portion of the anterior skim cut.

The saw blade 170 is then moved along the previously cut surfaces on thedistal end portion of the femur 126 to guide the saw blade duringcompletion of the anterior skim cut. Utilizing cut surfaces formedduring an initial portion of the anterior skim cut to guide the sawblade 170 enables the size of the anterior resection guide 138 to beminimized. Although the illustrated saw blade 170 has teeth 180 at onlyone end, the saw blade could also have teeth along oppositelongitudinally extending edges.

By utilizing the anterior resection guide 138 to guide movement of thesaw blade 170 during only an initial portion of forming the anteriorskim cut on the distal end portion 124 of the femur 126, the overalllength of the anterior resection guide, that is, the distance betweenthe ends 160 and 162 (FIG. 11) of the anterior resection guide can belimited to a distance which is less than the distance between theepicondyles 148 and 150. Specifically, the distance between the ends 160and 162 of the anterior resection guide 138 is less than two thirds (⅔)of the distance between the tips 144 and 146 of lateral and medialepicondyles 148 and 150 on the distal end portion 124 of the femur 126.By limiting the length of the anterior resection guide 138, the size ofthe incision 114 can be minimized.

It is contemplated that the initial portion of the anterior skim cutcould be made with a first cutting tool and the anterior skim cutcompleted with a second cutting tool. The initial portion of theanterior skim cut may be made with relatively small oscillating sawblade. The final portion of the anterior skim cut may be made with alarger reciprocating saw blade. Alternatively, a small milling cuttercould be used to make the initial portion of the anterior skim cut. Thefinal portion of the skim cut could be made with a relatively longmilling cutter or saw blade. It may be desired to make the initialportion of the anterior skim cut with a chisel and to complete theanterior skim cut with either a saw blade or a milling cutter.

The illustrated anterior resection guide 138 has a slot which forms theguide surface 178. This results in the saw blade 170 being captured sothat the saw blade is restrained against both up and down movement (asviewed in FIG. 11) relative to the anterior resection guide 138.However, in order to reduce the size of the anterior resection guide138, the slot could be eliminated and the saw blade 170 moved along aflat outer side of the anterior resection guide.

During making of the anterior skim cut, with and without the anteriorresection guide 138, body tissue (FIG. 9) overlies at least portions ofthe lateral and medial condyles being cut. This is due to the relativelyshort extent of the incision 114. Thus, the saw blade 170 and theportion of the femur 126 being cut by the saw blade are both at leastpartially enclosed by body tissue overlying the femur during making ofthe anterior skim cut. During making of the anterior skim cut, theincision 114 is moved relative to the femur 126 to provide clearance forthe saw blade.

After the anterior portion of the lateral and medial epicondyles havebeen cut away and the anterior resection guide 138 removed, a flatanterior cut surface 182 (FIGS. 14 and 15) is disposed on the distal endportion 124 of the femur 126. The anterior skim cut is made on thedistal end portion 124 of the femur 126 with the patella 120 offset toone side of the incision 118 (FIG. 14). The inner side of the patella120 faces toward the distal end portion 124 of the femur 126 when thepatella is in the offset position of FIGS. 9 and 14.

The flat anterior cut surface 182 (FIG. 15) extends parallel to theepicondylar axis. The maximum width of the anterior cut surface 182, asmeasured parallel to the epicondylar axis, is greater than the distancebetween opposite ends 154 and 156 (FIG. 11) of the femoral alignmentguide 134. Similarly, the maximum width of the anterior cut surface 182(FIG. 15), as measured parallel to the epicondylar axis, is greater thanthe distance between opposite ends 160 and 162 (FIG. 11) of the anteriorresection guide 138. The anterior cut surface 182 is at least partiallycovered by body tissue which encloses the distal end portion of thefemur 126 (FIG. 14).

During making of the anterior skim cut, the patient 62 (FIG. 2) issupported in a supine position on the support surface 64. The upperportion 72 of the leg 70 is disposed above the support surface on theleg support 80. The lower portion 68 of the leg 70 extends downward fromthe support surface 64. The foot 74 (FIG. 3) of the patient is disposedbelow the support surface.

Throughout the making of the anterior skim cut and the formation of theflat anterior cut surface 182 (FIGS. 14 and 15) on the distal endportion 124 of the femur 126, the lower portion 68 of the leg 70 can besuspended from the upper portion 72 of the leg in the manner illustratedin FIG. 3. This results in the knee portion 76 of the leg 70 beingdistracted by the combined weight of the lower portion 68 of the leg andthe foot 74. At this time, the lower portion 68 of the leg 70 danglesfrom the upper portion 72 of the leg. If desired, a holder could beprovided to engage either the foot 74 and/or the lower portion 68 of theleg 70 to maintain the foot 74 and lower portion 68 of the leg in adesired position relative to the support surface 64.

Once the anterior skim cut has been completed, a distal resection guide186 is positioned relative to the flat anterior skim cut surface 182(FIG. 16). To position the distal resection guide 186 relative to thecut surface 182, a resection guide stand 190 is mounted on the femoralalignment guide 134 in the manner illustrated in FIG. 16. The distalresection guide 186 is connected with the resection guide stand 190 byrotating a locking knob 192. The distal resection guide 186 andresection guide stand 190 may be magnetized to assure correct assembly.Since the femoral alignment guide 134 is medially offset relative to thedistal end portion 124 of the femur 126, the distal resection guide 186is also medially offset relative to the distal end portion of the femur.

When the distal resection guide 186 is to be connected with theresection guide stand 190, the distal resection guide is moved betweenthe anterior skim cut surface 182 and body tissue overlying the anteriorskim cut surface (FIG. 14). Thus, due to the limited extent of theincision 114, skin and other body tissues are disposed over the anteriorskim cut surface 182. The distal resection guide 186 slides between theanterior skim cut surface 182 and the body tissue overlying the anteriorskim cut surface. A lower (as viewed in FIGS. 16, 17 and 18) major sideof the distal resection guide 186 engages the anterior skim cut surface182. The opposite or upper (as viewed in FIGS. 16, 17 and 18) major sideof the distal resection guide 186 is engaged by the body tissueoverlying the anterior skim cut surface 182 (FIG. 14). The surgeon movesthe incision 114 and/or the lower portion 68 of the leg 70 relative tothe distal end portion of the femur 126 to facilitate movement of thedistal resection guide 186 onto the anterior skim cut surface 182.

Once the distal resection guide 186 has been positioned in the desiredlocation on the flat anterior cut surface 182, the distal resectionguide 186 is secured in place with pins 196 and 198 (FIG. 16). At thistime, body tissue overlies the portion of the distal resection guide 186spaced from the distal end of the femur. The distal resection guide 186is medially offset from a central portion of the femur 126 and isaligned with the incision 114. The incision 114 (FIG. 14) is movedrelative to the distal end portion 124 of the femur 216 to enable thepins 196 and 198 to be forced into the distal end portion of the femur.

The femoral alignment guide 134 and resection guide stand 190 are thenseparated from the distal end portion 124 of the femur 126 (FIGS. 17 and18). As this is done, the resection guide stand 190 (FIG. 16) isseparated from the distal resection guide 186. Separation of theresection guide stand 190 from the distal resection guide 186 isaccomplished by rotating the knob 192 and moving the resection guidestand 190 upward (as viewed in FIG. 16) to disconnect the guide stand190 from the femoral alignment guide 134. The intramedullary rod 132 andfemoral alignment guide 134 are then removed from the femur 126. Thedistance between opposite ends 206 and 208 of the distal resection guide186 is less than two thirds (⅔) of the distance between tips 144 and 146(FIG. 11) of the lateral and medial epicondyles 148 and 150.

The distal resection guide 186, like the anterior resection guide 138,is down sized to enable the distal resection guide to move into the kneeportion 76 of the patient's leg 70 through a relatively small incision114. To enable the distal resection guide 186 to move into the incisionthrough a relatively small incision 114, opposite ends 206 and 208 (FIG.16) of the distal resection guide 186 are spaced apart by a distancewhich is less than the distance between the lateral and medialepicondyles 148 and 150 (FIG. 11) on the distal end portion 124 of thefemur 126. The distance between opposite ends 206 and 208 of the distalresection guide 186 is less than the distance which a femoral implantextends across the distal end portion 124 of the femur 126.

The distal resection guide 186 is offset medially relative to the distalend portion 124 of the femur 126. The incision 114 is also mediallyoffset relative to the distal end portion 124 of the femur 126. Thisresults in the central portion of the guide surface 202 being exposedthrough the incision 114. The lateral and medial edges of the incision114 overlap opposite ends 206 and 208 of the distal resection guide 186.The incision 114 also overlaps the anterior side, that is, the upperside as viewed in FIG. 16, of the distal resection guide. During cuttingwith the saw blade 170 (FIGS. 17 and 18), the incision 114 iselastically expanded with suitable retractors.

During making of the distal femoral cut, the saw blade 170 moves alongthe guide surface 202 (FIG. 17) on the distal resection guide 186. Theguide surface 202 on the down sized distal resection guide 186 has alength which is less than a transverse dimension of a cut to be made inthe distal end portion 124 of the femur 126. The saw 172 may be pivoted,in a manner illustrated schematically in FIG. 13, adjacent to oppositeends of the guide surface 202. This moves the cutting end of the sawblade 170 along an arcuate path to form a generally fan shaped distalfemoral cut. The saw 172 may be either a reciprocating or oscillatingsaw.

Due to the reduced size of the distal resection guide 186, the saw blade170 (FIGS. 17 and 18) is ineffective to complete the distal femoral cutwhile the saw blade is in engagement with the guide surface 202 (FIGS.16 and 17). Therefore, after an initial portion of the distal cut hasbeen made by moving the saw blade 170 along the guide surface 202, thedistal resection guide 186 is disconnected from the distal end portion124 of the femur 126 and the distal femoral cut is completed.

During completion of the distal femoral cut, surfaces formed during theinitial portion of the distal femoral cut are effective to guide the sawblade 170. The saw blade 170 (FIGS. 17 and 18) is moved into the sawkerf or slot formed during the initial portion of the distal femoralcut. As the saw blade 170 extends the initial portion of the distalfemoral cut, the saw blade slides along cut surfaces formed during theinitial portion of the distal femoral cut. Thus, cut surfaces formedduring movement of the saw blade 170 along the guide surface 202 areutilized to guide movement of the saw blade during completion of thedistal femoral cut.

The initial portion of the distal femoral cut may be made with a firstcutting tool and the final portion of the distal femoral cut may be madewith a second cutting. For example, the initial portion of the distalfemoral cut may be made with a relatively small oscillating saw bladewhich can be readily inserted through the incision 114 into engagementwith the distal resection guide 186. The final portion of the distalfemoral cut may be made with a larger saw blade which may be of thereciprocating type. It is contemplated that the initial and/or finalportion of the distal femoral cut may be made with a milling cutter. Itis also contemplated that a chisel may be used to make the initialand/or final portion of the distal femoral cut.

When the distal femoral cut is completed, a flat distal end surface 209extends across the distal end of the femur 126 (FIG. 17). The distal endsurface 209 extends perpendicular to the anterior cut surface 182. Themaximum width of the distal end surface 209, as measured parallel to theanterior cut surface 182 and epicondylar axis, is greater than thedistance between opposite ends 206 and 208 of the distal resection guide186. The trochlear groove of the femur extends through the distal endsurface 209.

The distal femoral cut can be formed with the patella 120 (FIG. 14)offset to one side of the incision 114 and with the inner side 122 ofthe patella facing toward the distal end portion 124 of the femur 126.In addition, the leg 70 of the patient can be in the orientationillustrated in FIGS. 2 and 3 with the foot 74 and lower portion 68 ofthe leg suspended from the upper portion 72 of the leg. The upperportion 72 of the leg is supported above the support surface 64 by theleg support 80.

A femoral cutting guide 210 (FIGS. 19 and 20) is then positioned on thedistal end portion 124 of the femur 126 and utilized to make femoralanterior, posterior and chamfer cuts in a known manner. The femoralcutting guide 210 is connected with the distal end portion 124 of thefemur 126 by two pins (not shown) in a known manner. The femoral cuttingguide 210 is down sized so that it has opposite ends which are spacedapart by distance which is less than a distance between the lateral andmedial epicondyles 148 and 150 (FIG. 11) on the distal end portion 124of the femur 126. The femoral cutting guide 210 is offset in a medialdirection from the center of the femur 126 (FIG. 20). The mediallyoffset position of the femoral cutting guide 210 is the result of themedially offset position of the incision 114 (FIG. 6).

The initial portion of the femoral anterior, posterior and chamfer cutsare made by moving the saw blade 170 or other cutting tool along guidesurfaces on the femoral cutting guide. Due to the relatively small sizeof the femoral cutting guide, the cuts cannot be completed while movingthe saw blade 170 or other cutting tool along guide surfaces on thefemoral cutting guide. Therefore, the femoral cutting guide 210 isseparated from the distal end portion 124 of the femur 126 and the cutsare completed while guiding movement of the saw blade 170 or othercutting tool with cut surfaces formed during the making of the initialportions of the femoral anterior, posterior and chamfer cuts. When thefemoral anterior, posterior and chamfer cuts are completed, the distalend portion 124 of the femur 126 will have the known configurationillustrated in FIGS. 22 and 23.

The femoral cutting guide 210 (FIGS. 19 and 20) may have the sameconstruction as a femoral cutting guide which is commercially availablefrom Howmedica Osteonics of 359 Veterans Boulevard, Rutherford, N.J. Thefemoral cutting guide may have the construction disclosed in U.S. Pat.No. 5,282,803 or 5,749,876. However, it is preferred to down size theknown femoral cutting guides to have a distance between opposite endswhich is less than two thirds (⅔) of the distance between tips 144 and146 (FIG. 11) of medial and lateral condyles 148 and 150 on the distalend portion 124 of the femur 126. This enables the femoral cutting guide210 to move through the incision 114.

Since the femoral cutting guide 210 is down sized, initial portions ofthe femoral anterior, posterior and chamfer cuts are made while guidinga saw blade or other cutting tool with the femoral cutting guide. Thesecuts are subsequently completed utilizing previously cut surfaces toguide the saw blade 170. To complete a cut in this manner, the saw blade170 or other cutting tool is moved along the previously cut surfaces toguide the saw blade as the cuts are extended.

During the making of the initial portions of the anterior, posterior andchamfer cuts with the femoral cutting guide 210 and the subsequentcompletion of the cuts without the femoral cutting guide, the kneeportion 76 of the leg 70 of the patient can be distracted by the weightof the lower portion 68 and foot 74 of the leg. Thus, the lower portion68 and foot 74 of the leg 70 are suspended from the upper portion 72 ofthe leg in a manner illustrated in FIGS. 2 and 3 during the making ofthe femoral anterior, posterior and chamfer resections. The upperportion 72 of the patient's leg 70 is supported above the supportsurface 64 by the leg support 80 (FIG. 2).

By distracting the knee joint during the making of the femoral anterior,posterior and chamfer cuts, access to the distal end portion 124 of thefemur 126 is promoted and the making of the cuts is facilitated. Accessto the distal end portion 124 of the femur 126 is also promoted bymoving the suspended lower portion 68 of the leg 70 relative to thedistal end portion of the femur. The incision 114 may be moved relativeto the distal end portion 124 of the femur 126 by applying force to bodytissue adjacent to the incision.

Tibial Procedure

As was the case for femoral preparation, the tibial procedure can beperformed with the leg 70 in the position shown in FIGS. 2 and 3. Sincethe knee portion 76 of the leg 70 is distracted, a proximal end portion212 (FIG. 21) of a tibia 214 is separated from the distal end portion124 of the femur 126. The foot 74 (FIG. 3) may be moved posteriorly tohyperflex the knee portion 76. This facilitates viewing of the proximalend portion 212 of the tibia 214 through the relatively small incision114.

When the knee portion 76 (FIG. 2) is hyperflexed, the angle between theupper portion 72 and the lower portion 68 of the patient's leg 70 isless than ninety (90) degrees. At this time, the foot 74 is disposedposteriorly of the position illustrated in FIG. 2. This results in theproximal end portion 212 (FIG. 21) of the tibia 214 being movedanteriorly relative to the distal end portion 124 of the femur 126. Thedistal end portion 212 of the tibia 214 can then be viewed throughlimited incision 114. Even though the incision 114 has a relativelyshort length, it is possible to move the incision relative to theproximal end portion 212 of the tibia 214. Therefore, the entire or atleast almost the entire, proximal end surface of the tibia 214 can beviewed through the incision 214.

It is contemplated that an external tibial alignment guide (not shown)will be utilized to align a tibial resection guide 218 (FIG. 21) withthe proximal end portion 212 of the tibia 214. The tibial alignmentguide has a known construction and may be similar or the same as iscommercially available from Howmedica Osteonics of 359 VeteransBoulevard, Rutherford, N.J. Alternatively, the tibial alignment guidemay have the construction disclosed in U.S. Pat. No. 5,578,039; or5,282,803.

Once the tibial resection guide 218 (FIG. 21) has been aligned with andsecured to the proximal end portion 212 of the tibia 214, the externaltibial alignment guide (not shown) is disconnected from the tibialresection guide 218. The tibial resection guide 218 is secured to theproximal end portion 212 of the tibia 214 by suitable pins.

In accordance with one of the features of the present invention, thetibial resection guide 218 is relatively small so that it can be movedthrough a relatively small incision 114 into engagement with theproximal end portion 212 of the tibia 214. To facilitate moving of thetibial resection guide 218 through a relatively small incision 114, thetibial resection guide 218 is smaller than implants 286 (FIG. 27) and294 (FIG. 28) to be positioned on the proximal end portion 212 of thetibia 214. The tibial resection guide 218 has a distance betweenopposite ends 228 and 230 (FIG. 21) which is less than two thirds (⅔) ofthe distance between tips of lateral and medial epicondyles on the tibia214. Similarly, the distance between the ends 228 and 230 of the tibialresection guide 218 is less than two thirds (⅔) of the distance betweentips 144 and 146 (FIG. 11) of the lateral and medial condyles 148 and150 on the femur 126.

During positioning of the external tibial alignment guide and the tibialresection guide 218 (FIG. 21) relative to the tibia 214 in the leg 70 ofthe patient, the leg 70 can be supported in the manner illustrated inFIGS. 2 and 3. Thus, the upper portion 72 (FIG. 2) of the leg 70 issupported above the support surface 64 by the leg support 80. The lowerportion 68 of the leg 70 is suspended from the upper portion 72 of theleg. The foot 74 (FIG. 3) connected with the lower portion 68 of the leg70 is disposed below to support surface 64 (FIG. 2).

During positioning of the tibial resection guide 218 on the proximal endportion 212 of the tibia 214, the tibial resection guide is movedbetween the proximal end portion of the tibia and body tissue overlyingthe proximal end portion of the tibia. The tibial resection guide 218 ispositioned relative to the proximal end portion 212 of the tibia 214while the incision 114 is resiliently expanded. The incision 114 isexpanded by applying force against opposite sides of the incision withsuitable retractors. The retractors may have a construction similar tothe construction disclosed in U.S. Pat. No. 5,308,349. Alternatively, apneumatic retractor, such as is disclosed in U.S. patent applicationSer. No. 09/526,949 filed Mar. 16, 2000 by Peter M. Bonutti may be usedto expand the incision 114.

The tibial resection guide 218 is slid inferiorly, that is, downward (asviewed in FIG. 21) between the proximal end portion 212 of the tibia 214and body tissue adjacent to the proximal end of the tibia. The tibialresection guide 218 is then connected to the proximal end portion 212 ofthe tibia 214 with suitable pins. Once the resection guide 218 has beenconnected with the tibia 214, the force applied against opposite sidesof the incision 114 by retractors is interrupted and the incisioncontracts. As this occurs, the body tissue moves over the lower (asviewed in FIG. 21) portion of the tibial resection guide 218 to furtherenclose the tibial resection guide.

The tibial resection guide 218 is medially offset relative to theproximal end portion 212 of the tibia 214. This is because the incision114 is medially offset relative to the proximal end portion 212 of thetibia 214. The incision 114 extends from the proximal end portion 212 ofthe tibia 214 to the superior portion of the trochlear groove in thedistal end portion 124 of the femur 126. As was previously mentioned,the incision 114 and the instrumentation may be laterally offsetrelative to the femur 126 and the tibia 214.

Once the tibial resection guide 218 (FIG. 21) has been mounted on aproximal end portion 212 of the tibia 214, a proximal tibial cut ismade. The proximal tibial cut is made by moving the blade 170 of the saw172 along a guide surface 242 on the tibial resection guide 218 (FIG.21). When the saw blade reaches an end portion of the tibial guidesurface 242, the saw 172 is pivoted to move the saw blade 170 in themanner illustrated schematically in FIG. 16. This pivotal movementresults in the cutting end portion of the saw blade 170 having anarcuate component of movement. This results in a generally fan shapedcut being formed in the proximal end portion 212 of the tibia 214.

Due to the reduced size of the tibial resection guide 218 to facilitatemovement of the tibial resection guide through the incision 114, the saw172 can only form an initial portion of the proximal tibial cut as thesaw blade 170 moves along the guide surface 242 of the tibial resectionguide 218. To complete the proximal tibial resection cut, the tibialresection guide 218 is disconnected from the tibia 214.

Once the tibial resection guide 218 has been separated from the tibia214, the saw blade 170 is inserted into the slit or kerf made by the sawblade during the initial portion of the proximal tibial cut. The cutsurfaces which were formed during an initial portion of making theproximal tibial cut on the tibia 214 are then used to guide the sawblade 170 during completion of the proximal tibial cut. Thus, the sawblade 170 is moved along surfaces formed during the making of theinitial portion of the proximal tibial cut to guide movement of the sawblade during completion of the proximal tibial cut.

It is contemplated that different cutting tools may be utilized to makethe initial and final portions of the proximal tibial cut. Thus, the sawblade 170 used to make the initial portion of the tibial cut may be arelatively small oscillating blade and the saw blade used to make thefinal portion of the tibial cut may be a relatively long reciprocatingblade. Alternatively, the initial and/or final portion of the tibial cutmay be made with a milling cutter. If desired, a chisel could beutilized to make the initial portion of the tibial cut. The incision 114may be expanded with suitable retractors during making of the tibialcut. The retractors may have any desired construction, including theconstruction disclosed in U.S. Pat. No. 5,308,349. Ligaments and otherbody tissue adjacent to the proximal end portion 212 of the tibia 214may be shielded with suitable surgical instruments during making of thetibial cut.

Upon completion of the proximal tibial cut on the proximal end portion212 of the tibia 214, a flat proximal tibia cut surface 246 (FIG. 22) isexposed on the proximal end portion 212 of the tibia 214 through theincision 114. The flat cut surface 246 has a maximum width, as measuredalong an axis extending parallel to an axis extending through centralaxes of the collateral ligaments, which is greater than the distancebetween opposite ends 228 and 230 of the tibial resection guide 218. Thedistal end portion 124 of the femur 126 is also exposed through theincision 118.

In order to increase exposure of the proximal end portion 212 of thetibia 214 at the incision 218, the foot 74 and lower portion 68 of theleg 70 (FIG. 24) can be moved posteriorly toward the operating table 66(FIG. 2) to hyperflex the knee portion 76 of the patient's leg 70 duringthe making of the proximal tibial cut. When the knee portion 76 of theleg 70 is hyperflexed, the ankle 86 is moved from a position eitherextending through or anterior of a vertical plane extendingperpendicular to a longitudinal central axis of the upper portion 72 ofthe patient's leg 70 to a position disposed posteriorly of the verticalplane. Thus, as viewed in FIGS. 2 and 24, the ankle 86 is moved towardthe left. As this occurs, an angle between a longitudinal central axisof the upper portion 72 of the patient's leg and the longitudinalcentral axis of the lower portion 68 of the patient's leg is decreasedto an angle of less than ninety degrees.

Hyperflexing the patient's leg 70 moves the proximal end portion 212(FIGS. 22 and 23) of the tibia 214 anteriorly away from the distal endportion 124 of the femur 126. At this time, the knee portion 76 of thepatient's leg is distracted under the influence of the weight of thelower portion 68 of the patient's leg and the foot 74 connected with thelower portion of the patient's leg. If desired, a force pulling thelower portion of the patient's leg downward (as viewed in FIG. 3) may beapplied to the patient's leg to further increase the distraction of theknee portion 76 of the leg and the extent of exposure of the proximalend portion 212 of the tibia 214.

By hyperflexing the knee portion 76 of the patient's leg 70 and applyinga downward (as viewed in FIG. 3) force against the lower portion 68 ofthe patient's leg, the proximal end portion 212 of the tibia 214 isdelivered anteriorly that is, toward the surgeon 106 (FIG. 24).Application of a downward force against the lower portion 68 of thepatient's leg is effective to open the space between the proximal endportion 212 of the tibia 214 and the distal end portion 124 of the femur126 to the maximum extent permitted by the tendons and ligaments, thatis, fibrous connective tissue, interconnecting the femur and tibia.

This enables the posterior cruciate ligament 250 (FIG. 23) to bechecked. In addition, access is provided to the posterior side of theknee portion 76 of the leg 70. The surgeon 106 (FIG. 24) can manuallyfeel the posterior portion of the knee joint. There is sufficient spacebetween the distal end portion 124 of the femur 126 and the proximal endportion 212 of the tibia 214 to enable the surgeon 106 to visually andtactilely check the posterior of the knee portion 76 of the patient'sleg 70.

Access to the posterior portion of the knee enables osteophytes, bonespurs and similar types of posterior soft tissue to be removed. Thisenables tissue which could block further flexion of the knee portion 76to be removed. In addition, it is possible to check the collateralligaments and other fibrous connective tissue associated with the knee.

At this time, the lower portion 68 of the leg 70 (FIGS. 23 and 24) issuspended from the upper portion 72 of the leg. Therefore, the lowerportion 68 of the leg 70 hangs from the upper portion 72. The foot 74may be supported on the surgeon's knee 252 (FIG. 24) or other surface.The foot 74 is free to move in any direction relative to the kneeportion 76. By raising or lowering his or her knee 252, the surgeon 106can move the tibia 214 relative to the femur 126 and vary the spacebetween the distal end of the femur and the proximal end of the tibia.

By varying force indicated by arrows 256 (FIG. 25), the vertical extentof space between the proximal end portion 212 of the tibia 214 and thedistal end portion 124 of the femur 126 (FIGS. 22 and 23) can be eitherincreased or decreased. The force 256 is varied by raising and loweringthe surgeon's knee 252. Increasing the space between the proximal endportion 212 of the tibia 214 and the distal end portion 124 the femur126 maximizes access to the posterior of the knee portion 76.

By moving the lower portion 68 of the leg 70 upward, the ligaments andother connective tissue between the tibia 214 and femur 126 are relaxed.This enables the lower portion 68 of the leg 70 to be rotated about itslongitudinal central axis, in a manner indicated by arrows 258 in FIG.25. Rotational movement of the lower portion 68 of the leg 70 about itscentral axis enables the surgeon to cheek the collateral ligaments andthe resistance encountered to rotation of the lower portion 68 of theleg relative to the upper portion 72.

In addition, the foot 74 can be pivoted in a clockwise direction (asviewed in FIG. 25) about the knee portion 76, in the manner indicated byarrow 259 in FIG. 25, to increase the extent of flexion of the kneeportion 76. Alternatively, the foot 74 can be pivoted in acounterclockwise direction about the knee portion 76 to decrease theextent of flexion of the leg 70.

The lower portion 68 of the leg 70 can also be moved sidewise, in themanner indicated by the arrow 260 in FIG. 25. When the lower portion 68of the leg 70 is moved in the manner indicated by the arrow 260, thelower portion of the leg is moved along a path extending through lateraland medial surfaces of the foot 74 and the lower portion 68 of the leg70. This enables the ligaments and other fibrous connective tissue inthe leg to be checked for a range of movement. Although the incision 114has not been shown in FIG. 25, it should be understood that the lowerportion 68 of the leg 70 can be moved in the directions indicated by thearrows in FIG. 25 when the knee portion 76 is in the conditionillustrated in FIGS. 22 and 23.

The illustrated instrumentation can be formed of a metal which enablesthe instrumentation to be sterilized and reused. For example, theinstrumentation could be formed of stainless steel. However, known metalinstruments are relatively heavy and bulky. This substantially increasestransportation expense.

It is contemplated that it may be desired to use the instrumentationonce and then dispose of the instrumentation. If this is done, theinstrumentation may be partially or entirely formed of relativelyinexpensive polymeric materials. Thus, the femoral resection guide 134,anterior resection guide 138, distal resection guide 186, femoralcutting guide 210, and/or tibial resection guide 218 could be formed ofinexpensive polymeric materials. If this was done, the guides could beused once and disposed of without being sterilized. In addition, thepolymeric guides would weigh substantially less than metal guides.

Implants

After the distal end portion 124 of the femur 126 has been prepared andthe proximal end portion 212 of the tibia 214 is prepared to receiveimplants (FIGS. 22 and 23) and prior to insertion of the implants, anynecessary work on the patella 120 may be undertaken. During work on thepatella, the leg 70 of the patient may be extended and the patella 120may be everted or flipped to the position illustrated in FIG. 7. Theinner side or articular surface 122 of the patella 120 faces outward andis exposed. Known surgical techniques are then utilized to cut thepatella 120 and position an implant on the patella in a known manner.This may be accomplished utilizing any one of many known devices andprocedures, such as the devices and procedures disclosed in U.S. Pat.Nos. 4,565,192; 5,520,692; 5,667,512; 5,716,360; and/or 6,159,246. Ifdesired any necessary work on the patella 120 may be undertaken afterthe femoral and tibial implants have been installed.

As an alternative to the above-described procedure in which patella 120is everted or flipped to the position illustrated in FIG. 7, patella 120can be resurfaced or otherwise worked upon while maintained in asubstantially non-everted, anatomic position. U.S. Pat. No. 6,174,314B1, the contents of which are incorporated herein by reference,discloses instrumentation and methods for in situ resurfacing of apatella.

Additionally, U.S. Pat. No. 5,163,949 and progeny, such as U.S. Pat.Nos. 6,358,266 B1, 6,277,136 B1, and 6,187,023 B1, discloses variousembodiments of retractors and method of dissecting tissue. Theseembodiments include fluid operated retractors, mechanical retractors,and combinations thereof. The retractors and methods disclosed in thisline of patents, which is incorporated herein by reference, can be usedfor patella procedures and/or visualization while the patella ismaintained in a substantially non-everted, anatomic position.

Once the femoral and tibial cuts have been made and the patellarepaired, femoral and tibial implants are installed in the knee portionof the leg 70. Prior to permanently mounting of the implants in the kneeportion 76 of the leg 70, trials are conducted, in a known manner, withprovisional femoral and tibial implants. The provisional femoral andtibial implants are releasably positioned relative to the distal endportion 124 of the femur 126 and the proximal end portion 212 of thetibia 214. As discussed in more detail below, the provisional implants(and/or instrumentation) can be made disposable and can be combined withthe cutting guides or other instrumentation so that separate, dedicatedprovisional implants are not required.

The provisional implants are intended to aid the surgeon 106 inassessment of the function and balance of the various ligaments. Thetrials enable the surgeon 106 to observe the relationship of theprovisional femoral and tibial implants relative to each other duringflexion and extension of the knee portion 76 of the leg 70. In oneembodiment, the lower portion 68 of the leg 70 is suspended from theupper portion 72 of the leg (FIGS. 2 and 3) during the trials with theprovisional implants. Therefore, the lower portion of the leg 68 can befreely moved relative to the upper portion of the leg to check ligamentbalancing with the provisional implants. Since the lower portion of theleg 68 is suspended, it is possible to check for flexion and extensionbalancing of the ligaments and to check for rotational stability androtational balancing of the ligaments during the trials with provisionalimplants. The lower portion 68 of the leg 70 can be moved with acombination of flexion or extension, rotation and sidewise movement.

The trials also enable the surgeon to check the manner in which theprovisional implants interact with each other during flexion, extension,rotation, and sidewise movement. The manner in which the provisionalfemoral and tibial implants move relative to each other during combinedbending and rotational movement of a patient's leg 70 enables a surgeonto check for the occurrence of excessive space or other undesirablesituations between the provisional implants. During trials withprovisional implants, the range of motion of the knee joint can bechecked in both flexion/extension and rotation.

Utilizing known surgical techniques, it is very difficult, if notimpossible, to check for both flexion/extension balancing, rotationalbalancing, and sidewise balancing during trials with provisionalimplants. With rotational balancing, the ligaments are balanced throughmultiple planes. When both flexion/extension and rotation are beingchecked, the surgeon can locate defects and improve the stability of theknee joint. The surgeon can assess the posterior cruciate ligament,collateral ligament balancing, and posterior capsule balancing. Thesurgeon can proceed with flexion/extension balancing of ligaments androtational balancing of the ligaments. This enables the leg 70 to beexamined throughout its range of motion during trials with provisionalimplants.

During an operation on the patient's leg 70, the surgeon can applyupward force against the foot of the patient by resting the foot 74 onthe surgeon's knee 252 (FIG. 24) and raising the knee of the surgeon. Ofcourse, when the foot 74 is to be lowered, the surgeon can lower theknee 252 upon which the foot 74 of the patient is resting.Alternatively, a pneumatic piston can be utilized to raise and lower thefoot 74 of the patient.

Throughout the operation on the patient's knee 76, the upper portion 72of the patient's leg 70 is supported above the support surface 64 by theleg support 80. This causes the hip of the patient to be hyperflexed bybetween 20 degrees and 40 degrees. Flexing of the hip by 20 degrees to40 degrees improves rotational positioning and alignment. It alsoenhances the ability of the surgeon to hyperflex the knee portion 76 orto extend the knee portion during surgery. In addition, having the upperportion 72 of the patient's leg supported above the support surface 64by the leg support 80 improves suspension of the lower portion 68 of theleg from the upper portion 72 of the leg. It is believed that thecombination of suspending the lower portion 68 of the leg 70 and havingthe upper portion 72 of the leg supported above the support surface 64by the leg support 80 will enhance the ability of a surgeon to checkligament balancing in flexion/extension, and rotation during trialsduring which provisional femoral and tibial components are temporarilyconnected with the distal end portion 124 of the femur 126 and with theproximal end portion 212 of the tibia 214.

During a portion of the trials, the patella 120 may be in the normalposition relative to the distal end portion 124 of the femur 126 and theproximal end portion 212 of the tibia 214. Therefore, during trials, itis possible to check tracking of the patella relative to the provisionalfemoral implant. This is done in order to prevent any possibleinterference of the patella 120 with the movement of the knee throughits range of motion.

To install the trial femoral and tibial components, the proximal endportion 212 of the tibia 214 is prepared to receive the trial tibialimplant. This is accomplished by positioning a tibial trial base plate270 on the proximal end portion 212 of the tibia 214 (FIG. 26). Analignment handle 272 is connected with the tibial trial base plate 270to facilitate positioning of the tibial trial base plate relative to theproximal end portion 214 of the tibia.

The trial femoral implant (not shown) is then placed on the distal endportion 124 of the femur. This may be done in a known manner using afemoral impactor/extractor. A trial tibial bearing insert (not shown) isthen mounted on the tibial trial base plate 270 in a known manner. Oncethis has been done, the trial provisional implants are used duringconducting of trials with flexion/extension and rotational movements ofthe lower portion 68 of the patient's leg. When the trials arecompleted, the trial provisional implants are removed in a known manner.

After completion of the trials, the tibial trial base plate 270 ispinned to the proximal end portion 214 of the tibia. A tibial punch 274(FIG. 26) is positioned in a tibial punch tower (not shown) which isassembled onto the tibial trial base plate 270. The tibial punch 274 isadvanced relative to the tibial punch tower by impacting a malletagainst the tibial punch. The foot 74 rests against the knee 252 of thesurgeon during pounding of the tibial punch 274 into the tibia 214. Thisresults in the impaction forces being transmitted to the surgeon's knee252 rather than to ligaments interconnecting the femur 126 and tibia214.

Once the tibial punch 274 has been advanced until it is fully seated onthe base plate, the punch is removed. The tibial trial base plate 270 isthen removed from the proximal end portion 214 of the tibia. Once thetibial trial base plate 270 has been removed, an opening 282 (FIG. 27)formed in the proximal end portion 212 of the tibia 214 is exposed. Theopening 282 has a configuration corresponding to the configuration ofthe tibial punch 274.

A tibial tray 286 (FIG. 27) forms a base portion of a tibial implant.The tibial tray 286 has a keel 288 with a configuration corresponding tothe configuration of the tibial punch 274 (FIG. 26) and the opening 282(FIG. 27) formed in the tibia 214. The keel 288 (FIG. 27) of the tibialtray 286 is covered with a suitable cement prior to being inserted intothe opening 282. If desired, the cement may be omitted.

A tibial component impactor/extractor may be used to insert the tibialtray 286 into the opening 282. Once the tibial tray 286 has been mountedon the proximal end portion 212 (FIG. 28) of the tibia 214, a femoralcomponent 290 (FIG. 29) is mounted on the distal end portion 124 of thefemur 126. A known femoral impactor/extractor may be used to positionthe femoral component 290 on the distal end portion of the femur. Thefemoral component 290 may be provided with or without an intramedullarystem. Cement may or may not be used in association with the femoralcomponent 290. Once the femoral component 290 has been mounted on thedistal end portion 124 of the femur 126, a tibial bearing insert 294(FIGS. 28 and 29) is positioned in the tibial tray.

The femoral and tibial implants 286, 290, and 294 may have any one ofmany known constructions. For example, the femoral and tibial implantscould have the construction of a knee replacement which is commerciallyavailable from Howmedica Osteonics of 359 Veterans Boulevard,Rutherford, N.J. under the designation of “Scorpio” (trademark) totalknee. Rather than being a total replacement, the femoral and tibialimplants could be for a partial knee replacement. Thus, the femoral andtibial implants 286, 290 and 294 could have a construction which is thesame as is illustrated in U.S. Pat. No. 5,514,143. The femoral andtibial implants 286, 290 and 294 may be of either the cemented type orthe cementless types.

Once the femoral component 290 has been positioned on the femur 126 andthe tibial tray 286 and bearing insert 294 positioned on the tibia 214,ligament balancing is again conducted. The ligament balancing includes acheck of stability of the joint in flexion, extension, and rotation. Theligament balancing check is performed with the lower portion 68 of theleg 70 suspended from the upper portion 72 of the leg. The upper portion72 of the leg 70 is held above the support surface 64 (FIG. 2) by theleg support 80 during the ligament balancing.

Since the lower portion 68 of the leg 70 is suspended from the upperportion 72, in the manner illustrated in FIGS. 2, 3 and 25, the surgeonhas a more natural feel of the true ligamentous structure. This isbecause tissues are not squashed or bunched in the back of the kneeportion 76. Since the lower portion 68 of the leg 70 is suspended fromthe upper portion 72 of the leg, the joint 76 is distracted withouthaving the lower portion 68 of the leg jammed back against the upperportion 72 of the leg. With the leg suspended, a surgeon can view thetibial bearing insert 294 (FIG. 29) and the femoral component 290 todetermine how the femoral and the tibial implants cooperate with eachother and the ligaments, tendons, joint capsule and other tissues.

The knee portion 76 may be flexed and extended, by moving the lowerportion of the leg 70 along the path indicated by arrow 259 in FIG. 25.In addition, the lower portion 68 of the leg 70 may be moved sideways,that is, laterally and/or medially, as indicated by arrow 260 in FIG.25, to check for the occurrence of slight openings between the tibialbearing insert 294 (FIG. 29) and femoral component 290. The lowerportion 68 of the leg can also be rotated about its longitudinal centralaxis, in the manner indicated by the arrow 258 in FIG. 25. Bysimultaneously applying a combination of rotational, sideward, andflexion or extension motion to the lower portion 68 of the leg 70, thesurgeon can view the interaction between the tibial bearing insert 294(FIG. 29) and femoral component 290 through the entire range of movementof the leg 70, including movement having rotational components.

By manually feeling resistance to flexion, rotational and/or sidewardmovement of the lower portion 68 of the patient's leg 70 (FIG. 25), thesurgeon can check the balancing of ligaments and other tissues in theknee portion 76 of the leg. In addition, the surgeon can check themanner in which relative movement occurs between the tibial bearinginsert 294 and femoral component 290 (FIG. 29). If a cheek of therotational alignment of the femoral and tibial implants indicates thatthey are misaligned, the surgeon can change the rotational positions ofthe implants. If the ligaments are too tight medially or laterally, thesurgeon can release the ligaments to the extent necessary. Ligamentswhich are too loose can be tightened. Since the lower portion 68 of theleg 70 is suspended, the surgeon can feel the effects of any ligamentousimbalance and take corrective action.

In contrast to the present invention, the majority of kneearthroplasties are done with the leg in a fixed position. Surgeons donot flex and extend through progressive intervals. As the abovediscussion illustrates, one aspect of the present invention involvescontrolling the position of the joint so that when the surgeon wants towork on the quadriceps mechanism the knee is in full extension.Similarly, when the surgeon wants to work on the tibia then he may be inmore flexion, more toward 90-100.degree. The controlled positioning canbe done in a leg alignment jig which allows reproducible holdingpositions that can be adjusted as desired. As previously noted, this canbe achieved with electric motor, pneumatics, mechanical, or simpleratchets built on to a table, but allow precise positioning of the legwhile surgeon goes from flexion to extension. There are existing legholders, but these are very crude. Most surgeons simply use a sandbagand hold the leg in one position. This position is not preciselycontrolled, and therefore, somewhat variable. The soft tissue sleeve andrelaxation is critical as one goes from flexion to extension, is morerelaxed depending on which portion of the joint you want to expose,varying from flexion to extension. Certainly, quadriceps mechanism isthe most relaxed in full extension, tighter against the femur inflexion. The tibia exposure may be improved in flexion, but controllingthe specific amount of flexion/extension, locking this into positionwhile the cuts are being performed sequentially and precisely is ofsignificant value.

A portion of the foregoing check of ligamentous balancing may beperformed with the patella 120 offset to one side of the incision 114,in the manner illustrated in FIG. 29. This enables the surgeon to have aclear view of the tibial bearing insert 294 and femoral component 290through the open incision 114. After conducting a complete check of theligamentous balancing with the patella 120 offset to one side of itsnatural position, the patella can be moved back to its natural position.

When the patella 120 is moved back to its natural position, the incision114 closes so that there is little or no exposure of the tibial bearinginsert 294 and femoral component 290 to the view of the surgeon.However, the surgeon 106 can move the lower portion 68 of the leg 70with flexion/extension motion, indicated by the arrow 259 in FIG. 25,and/or rotational motion, indicated by the arrows 258, or sidewaysmotion indicated by arrows 260. During this motion of the lower portion68 of the leg 70, the surgeon can check the manner in which the patella120 interacts with the tibial and femoral implants and other tissues inthe knee portion 76 of the patient's leg. By providing combinations ofthe foregoing rotational and flexion/extension motion of the lowerportion of the leg 70, the manner in which the patella 120, with orwithout an implant thereon, tracks relative to the tibial and femoralimplants can be readily checked.

In the foregoing description, the patella 120 was repaired after makingthe femoral and tibial cuts and before trials. However, it iscontemplated that the patella 120 may be repaired after trials and afterinstallation of the implants 286, 290 and 294. Of course, the patella120 may not need to be repaired and will be maintained in its originalcondition.

It is contemplated that fluid operated devices may be utilized torelease ligaments or other tissue. The fluid operated devices may beutilized to apply force to tissue to move tissue relative to a bone, toexpand the tissue, or to lengthen the tissue. For example, a balloon orbladder may be placed between tissue at the posterior of the kneeportion 76 prior to mounting of the implants 286, 290 and 294. Theballoon may be inflated with gas or the bladder filled with liquid tomove tissue relative to the distal end portion 124 of the femur 126 andrelative to the proximal end portion 212 of the tibia 214. The balloonor bladder may be used to move tissue before or after making of thefemoral and/or tibial cuts. The balloon or bladder may be used to movetissue before or after the trial implants are positioned in the kneeportion 76. The balloon or bladder may be used to move tissue before orafter the implants 286, 290 and 294 are positioned in the knee portion76.

The balloon or bladder may be formed of biodegradable ornon-biodegradable material. If the balloon or bladder is formed ofbiodegradable material, it may be left in the knee portion during andafter closing of the incision 114. Of course, the biodegradable balloonor bladder will eventually be absorbed by the patient's body. In thisregard, a narcotic or other medicament may be incorporated in thematerial in the balloon or the fluid used to expand the balloon. Thisprovides a gradual time release of the medicament as the balloondegrades. Regardless of whether the device is biodegradable, capsulartightening and capsular tissue can be expanded or stretched. In thedevice is left in postoperatively, the balloon or bladder provides forhemostasis and maintenance of the soft tissue sleeve to improveflexion/extension.

It is contemplated that fluid operated retractors, expanders, and/ordissectors may be used to retract, expand or dissect body tissue. Forexample, retractors having a construction similar to any one of theconstructions disclosed in U.S. Pat. No. 5,197,971 may be utilized torelease tissue at locations spaced from the incision 114. When tissue isto be released at locations where there is limited accessibility fromthe incision 114, a device similar to any one of the devices disclosedin U.S. Pat. No. 5,295,994 may be utilized. It is believed that devicessimilar to those disclosed in U.S. patent application Ser. No.09/526,949 filed Mar. 16, 2000 may be used in ways similar to thosedisclosed therein to move and/or release body tissue.

While the lower portion 68 of the leg 70 is suspended from the upperportion 72 of the leg and while the upper portion of the leg is heldabove the support surface 64 by the leg support 80, the incision 114 inthe knee portion 76 of the leg 70 is closed. Prior to closing of theincision 114, the incision is thoroughly drained. Tissues in the kneeportion 78 are then interconnected using a suture or other suitabledevices. The soft tissues are closed in a normal layered fashion.

Review

With the exception of the procedure on the patella 120 (FIG. 7), all ofthe foregoing procedures may be performed with the leg 70 of the patientin the orientation illustrated in FIGS. 2, 3 and 25. Thus, with theexception of procedures on the patella 120, all of the foregoingprocedures may be conducted with the lower portion 68 of the leg 70suspended from the upper portion 72 of the leg.

The incision 114 (FIG. 7) was made in the knee portion 76 of the leg 70with the lower portion 68 of the leg suspended. Similarly, the incision114 in the knee portion of the leg 70 was closed with the lower portion68 of the leg suspended from the upper portion 72 of the leg. Thus, fromthe making of the incision 114 in the knee portion 76 of the leg 70through the closing of the incision, the lower portion 68 of the leg isalmost continuously extended downward from the upper portion 72 of theleg and the foot 74 was below the support surface 64. In addition, theupper portion 72 of the leg was supported above the support surface 64by the leg support 80. Only during everting of the patella 120 (FIG. 7)and resecting of the patella to receive an implant was the leg 70 of thepatient in an extended or straightened orientation. However, the leg 70of the patient could be extended or straightened at any time the surgeondesires during the foregoing procedure.

Throughout the entire procedure, the drapery system 100 (FIGS. 4 and 5)maintained a sterile field between the surgeon 106 and the patient. Asthe surgeon moved between seated and standing positions and moved towardor away from the patient, the drape 102 would rise or fall. Thus, whenthe surgeon 106 moves from the seated position of FIG. 4 to the standingposition of FIG. 5, the drape 102 tends to rise upward with the surgeon.Similarly, when the surgeon moves from the standing position of FIG. 5back to the seated position of FIG. 4, the drape 102 tends to movedownward. The drape 102 will tend to move upward as the surgeon movesaway from the leg 70 of the patient and will tend to move downward asthe surgeon moves toward the leg 70 of the patient. Although it ispreferred to use the drapery system 100 illustrated in FIGS. 4 and 5 andthe various other embodiments described in connection with thesefigures, it is contemplated that a different drapery system could beutilized if desired.

It is believed that it will be particularly advantageous to utilize downsized instrumentation in performing the foregoing procedures on the kneeportion 76 of the patient. The femoral alignment guide 134 (FIGS.10-15), anterior resection guide 138 (FIGS. 10-13), resection guidestand 190 (FIG. 16), distal resection guide 186 (FIGS. 16-18), andtibial resection guide 218 (FIG. 21) all have sizes which are two thirds(⅔) of their normal sizes or smaller. However, the various down sizedinstrumentation components of FIGS. 9-21 can be utilized in their normalmanner and have generally known constructions. Thus, the instrumentationof FIGS. 9-21, with the exception of being down sized, is generallysimilar to known instrumentation which is commercially available fromHowmedica Osteonics Corp. of Rutherford, N.J. under the trademark“Scorpio” single access total knee system.

As was previously mentioned, it is contemplated that extramedullaryand/or intramedullary instrumentation could be utilized if desired.Although it is believed that it may be preferred to use instrumentationwhich is anteriorly based, it is contemplated that posteriorly basedinstrumentation systems could be used if desired. Additionally and asdescribed below, lateral or medial based instrumentation could be usedif desired. The present invention also envisions combinations of thesevarious instrumentations.

In the foregoing description, the saw 172 and blade 170 (FIG. 15) wereutilized to make cuts in various bones in the knee portion 76 of the leg70 of the patient. The saw 172 and blade 170 may be of either theoscillating or reciprocating type. However, it is contemplated thatother known cutting instruments could be utilized. For example, amilling device could be utilized to form at least some of the cuts.Alternatively, a laser or ultrasonic cutter could be utilized in makingsome of the cuts. It is believed that it may be particularlyadvantageous to utilize a laser or ultrasonic cutter to initiate theformation of a cut and then to utilize a saw or other device to completethe cut.

It is contemplated that either extramedullary or intramedullaryinstrumentation having a construction which is different than theillustrated construction could be utilized. For example, the anteriorresection guide 138 FIGS. 10, 11 and 12 has a guide surface 178 which isformed by a slot through which the saw blade extends. If desired, theguide surface 178 could be provided on an end face without providing forcapturing or holding of the saw blade 170 in a slot.

The instrumentation may be entirely or partially formed of light weightpolymeric materials which are relatively inexpensive. A femoral cuttingguide 210 has a size which corresponds to the size of the specificfemoral component 290 which is to be installed on the distal end portion124 of a femur 126. An inexpensive femoral cutting guide 210, formed ofpolymeric material, may be packaged along with a femoral component 290of the same size. After the femoral component 290 is installed, thefemoral cutting guide 210 may be discarded. This would minimizeinvestment in instrumentation and would tend to reduce the cost ofhandling and/or sterilizing cutting guides. The result would be areduction in cost to the patient.

It is contemplated that the use of guide members, corresponding to theanterior resection guide 138 of FIG. 11, the distal resection guide 186of FIG. 16, and the tibial resection guide 218 of FIG. 21 could beeliminated if desired. If this was done, positioning of a saw blade orother cutting device could be provided in a different manner. Forexample, light forming a three dimensional image, such as a hologram,could be projected onto the distal end portion 124 of the femur 126. Thethree dimensional image would have lines which would be visible on thesurface of the end portion 124 of the femur 126. The saw cut would beformed along these lines. Alternatively, robot type devices havingcomputer controls could be utilized to form the cuts without using guidemembers.

It is contemplated that emitters, receivers, and/or reflectors ofcomputer navigation systems could be pinned or otherwise attached ontothe femur 126 and tibia 214 to provide cutting positions and tofacilitate ligament balancing through relatively small incisions. Thecomputer navigation system may utilize three or four separate registerswhich have optical feedback to a central unit. The computer navigationsystem may utilize electromagnetic or photo-optical feedback.

It is contemplated that various known structures could be utilized inassociation with the leg 70 of the patient during performing of one ormore of the procedures described herein. For example, the apparatusdisclosed in U.S. Pat. No. 5,514,143 could be connected with the leg 70of the patient and used to control flexion and extension of the leg.Since the apparatus disclosed in U.S. Pat. No. 5,514,143 includesseparate femoral and tibial sections, it is believed that this apparatusmay be particularly well adapted for use with the leg of the patient inthe orientation illustrated in FIGS. 2, 3 and 25. This apparatus doesnot interfere with distraction of the knee portion 76 and canaccommodate flexion and extension of the leg 70 of the patient.

The foregoing description has primarily referred to a full kneereplacement. However, it is contemplated that the apparatus andprocedures disclosed herein may be utilized in association with arevision or partial knee replacement. For example, the method andapparatus disclosed herein could be utilized in association with aunicompartmental knee replacement of the type disclosed in theaforementioned U.S. Pat. No. 5,514,143. The method and apparatusdisclosed herein could be utilized in association with a revision of apreviously installed full or partial knee replacement. It is alsocontemplated that the procedures disclosed herein and apparatus similarto the apparatus disclosed herein may be utilized with many differenttypes of joints. For example, the procedures and apparatus may beutilized in association with a joint in an arm, shoulder, spine or hipof a patient.

Support Assembly

In accordance with one of the features of the invention, a supportassembly 330 (FIG. 30) is provided for the lower portion 68 of the leg70 of the patient. Rather than support the foot 74 of the patient on theknee 252 of the surgeon (FIG. 24), as previously described herein, thesupport assembly 330 may be utilized. The support assembly 330 includesa flat surface 332 which engages the foot of the patient. Apneumatically actuated piston and cylinder assembly 334 is operable toraise and lower the foot 74 of the patient in the manner indicatedschematically by an arrow 336 in FIG. 31. Mechanisms other thanpneumatics, such as a motor, could be used to control piston andcylinder assembly 334.

When the knee portion 76 of the leg 70 is to be distracted, the pistonand cylinder assembly is operated to lower the surface 332 and foot 74of the patient. As this occurs, the weight transferred from the foot 74of the patient to the support surface decreases until the supportsurface 332 is below and spaced from the foot 74. Similarly, when theextent of distraction of the knee portion 76 is to be decreased, thepiston and cylinder assembly 334 is operated to raise the supportsurface 332 and foot 74 of the patient.

By providing a flat support surface 332, the lower portion 68 of the legof the patient may be rotated about its longitudinal central axisrelative to the upper portion 72 of the leg of the patient when thesupport assembly 330 is being utilized to at least partially support thelower portion 68 of the leg of the patient. However, it is contemplatedthat a foot holder could be provided in place of the flat surface 332.The foot holder would have the advantage of being able to hold the foot74 of the patient in a desired orientation relative to the upper portion72 of the leg 70 of the patient. The foot holder could be constructed soas to have a pneumatically (or other) actuated drive to rotate the foot74 about the longitudinal central axis of the leg 70 and/or lowerportion 68 of the leg 70 of the patient.

The support surface 332 is raised and lowered by operation of the pistonand cylinder assembly 334. Therefore, operation of the piston andcylinder assembly 334 is effective to move the lower portion 68 of theleg 70 of the patient in the directions of the arrow 256 in FIG. 25. Itis contemplated that a drive assembly could be connected with thesupport surface 332 to rotate the support surfaces about a verticalaxis. The drive assembly may include a rack and pinion drive arrangementor a worm and wheel drive arrangement. By rotating the support surface332 about a vertical axis relative to the piston and cylinder assembly334, movement of the lower portion 68 of the leg 70 in the directions ofthe arrow 258 in FIG. 25 would be facilitated.

Percutaneous Instrumentation Mounting

In accordance with another feature of the invention, it is contemplatedthat the size of the incision 114 may be reduced by connecting one ormore of the guide members with one or more bones through the skin of thepatient. For example, the anterior resection guide 138 (FIGS. 10 and11), distal resection guide 186 (FIG. 16), femoral cutting guide 210(FIGS. 19 and 20), and/or tibial resection guide 218 (FIG. 21) could bemounted on the outside of the leg 70 and connected with bone in eitherthe upper portion 72 or the lower portion 68 of the leg 70 of thepatient. This would minimize or even eliminate the necessity of movingthe guide through the incision 114 into engagement with the bone. Itwould also minimize or even eliminate the necessity of sizing theincision 114 so as to accommodate the guide.

For example, the distal resection guide 186 (FIGS. 16-18) is illustratedschematically in FIG. 31 as being mounted outside of the upper portion72 of the leg 70 of the patient. The distal resection guide 186 isillustrated in FIG. 31 as being disposed in engagement with an outersurface of skin 342 which encloses the distal end portion 124 of thefemur 126. The distal resection guide 186 is mounted directly outward ofthe flat anterior cut surface 182 formed on the distal end portion 124of the femur 126. The skin 342 and other body tissue extends between thedistal resection guide 186 and the distal end portion 124 of the femur126.

The distal resection guide 186 is connected with the femur 126 by thepins 196 and 198. The pins 196 and 198 extend through the distalresection guide 186 and the skin 342 into the femur 126. The pins 196and 198 extend through the flat anterior cut surface 182 into the femur126 and hold the distal resection guide 186 against movement relative tothe femur 126.

Although a distal resection guide 186 has been illustrated in FIG. 31,it is contemplated that an anterior resection guide, corresponding tothe anterior resection guide 138 of FIG. 11 could be mounted in asimilar manner. If this were done, the anterior resection guide 138would have a generally L-shaped configuration with a body portion whichwould extend along the outer surface of the skin 342 (FIG. 31). Pins,corresponding to the pins 196 and 198 of FIG. 31, would extend throughthe relatively long body portion of the generally L-shaped anteriorresection guide 138, through the skin 342 and into the femur 126.

The short leg of the L-shaped anterior resection guide 138 would bepositioned adjacent to the distal end portion 124 of the femur 126. Theshort leg of the anterior resection guide would have a guide surfacealigned with the distal end portion 124 of the femur 126 at a locationcorresponding to the location where the flat anterior cut surface 182 isto be formed. This guide surface could be of the slot or capture typeillustrated in FIG. 14. Alternatively, the guide surface could be formedon a flat end face of the anterior resection guide. This would result inelimination of the slot commonly utilized to capture a saw blade orother cutting instrument. By having a portion of the anterior resectionguide disposed outside of the incision 114 and connected with the femur126 through the skin 342, the size of the incision 114 tends to beminimized.

In addition to the aforementioned guides associated with the femur 126,it is contemplated that a guide associated with the tibia 214 (FIG. 21)could be connected with the tibia by pins extending through the skin342. For example, the tibial resection guide 218 could be placed inabutting engagement with skin which overlies the proximal end portion212 of the tibia 214. Suitable pins would extend through the tibialresection guide 218 (FIG. 21) and through the skin 342 (FIG. 31) intoengagement with the distal end portion 212 of the tibia. Although it maybe preferred to provide a tibial guide surface 242 of the slot typeillustrated in FIG. 22, it is contemplated that only a single guidesurface could be provided on a flat end portion of the tibial resectionguide if desired.

Inspection

It is contemplated that at various times during the performance of theforegoing procedures, it may be desired to inspect locations remote fromthe incision 114. Thus, it may be desired to visually ascertain thecondition of soft tissue in the posterior of the knee portion 76. Inaddition, it may be desired to visually check the condition of thecollateral ligaments or soft tissue adjacent to the ligaments. Theinspections may be conducted before or after the making of femoral andtibial cuts, before or after trials, and/or before or after installationof the implants 286, 290 and 294.

In accordance with another feature of the invention, locations remotefrom the limited incision may be visually inspected. To inspectlocations remote from the incision 114, a leading end portion 350 (FIG.32) of an endoscope 352 can be inserted through the incision 114 andmoved to the posterior of the knee portion 76. Alternatively, theleading end portion 350 of the endoscope 352 can be inserted through asmaller stab wound incision. A camera 354 transmits an image to amonitor 356. The surgeon 106 can then view images of the posterior ofthe knee portion 76 transmitted through the endoscope 352. The upperportion 72 of the leg 70 is supported by the leg support 80. The leg 70is shown in FIG. 32 in the same position illustrated in FIGS. 2 and 3.

In order to provide the surgeon 106 with information as to how thefemoral and tibial implants 286, 290 and 294 interact with tissues inthe knee portion 76, the leg 70 of the patient may be bent between theflexed condition of FIG. 32 and the extended condition of FIG. 33. Inaddition, the lower portion 68 of the leg 70 may be rotated about itslongitudinal central axis, in the manner indicated by the arrow 258 inFIG. 25. During bending of the knee portion 76, the surgeon views imagesof the posterior knee portion transmitted through the endoscope 352 tothe monitor 356. This enables the surgeon to detect any present orpotential interference of tissue in the knee portion 76 with the fullrange of motion of the knee portion. During relative movement betweenthe femur 126 and tibia 214, the surgeon can view the manner in whichthe femoral and tibial implants interact with each other and the tissuein the joint capsule.

It is contemplated that the end portion 350 of the endoscope 352 will bemoved so as to enable the surgeon 106 to view the collateral ligaments,particularly the ligament on the lateral side of the knee portion 76,during bending of the knee portion. Although the endoscope 352 isillustrated in FIGS. 32 and 33 as being utilized after the femoral andtibial implants 286, 290 and 294 have been connected with the femur 126and tibia 214, it is contemplated that the endoscope will be utilizedprior to cutting of the femur and tibia, after cutting of the femur andtibia and prior to trials, after trials, and/or during trials.

It is contemplated that the endoscope 352 may be inserted into the kneeportion 76 of the patient at a location other than through the incision114. Thus, if desired, a separate, very small portal or puncture typeincision could be formed in the knee portion 76 of the leg of thepatient at a location adjacent to a location where it is desired tovisually inspect the knee portion of the patient. Although it isbelieved that it will be desired to inspect the knee portion 76 of thepatient while there is relative-movement between the femur 126 and tibia214, it should be understood that the endoscope 352 could be utilized toinspect the knee portion 76 while the femur 126 and tibia 214 arestationary relative to each other.

Although an endoscope 352 is illustrated in FIGS. 32 and 33, it iscontemplated that other known devices could be utilized to inspect kneeportion 76. Thus any desired fiber optic type instruments may beutilized to inspect the knee portion 76. For example any of the knowninstruments associated with arthroscopic surgery could be utilized toinspect the knee portion 76.

Generation of Images and Robotic Device

In accordance with another feature of the invention, during performanceof surgery on a knee portion 76 of a patient's leg 70 (FIG. 34), a knownC-arm fluoroscope 360 or other imaging system is utilized to generateimages of the knee portion 76 of the leg 70 during movement of the lowerportion 68 of the leg relative to the upper portion of the leg. Imagesare transmitted in any fashion from the C-arm fluoroscope 360 to acontrol unit 362. Video images are transmitted from the control unit 362to a video screen 364 which is viewable by the surgeon 106 duringsurgery on the knee portion 76 of the leg 70. A continuous display ofimages is projected in rapid succession on the screen illustrating theknee portion 76 of the leg 70 when the lower portion 68 of the leg is invarious positions relative to the upper portion of the leg.

Thus, during flexion and/or extension of the leg 70, video images aretransmitted to the screen 364 to enable a surgeon to view images of thedistal end portion 124 of the femur 126 and the proximal end portion 212of the tibia 214 during bending of the knee portion. The video displayof images may be undertaken prior to forming of the incision 114 toenable the surgeon to view the manner in which components of the kneeportion 76 interact prior to surgery. After the incision 114 has beenmade, the images provided on the video screen 364 enable the surgeon tovisually determine the relationship between the distal end portion 124of the femur 126 and the proximal end portion 212 of the tibia 214 afterthe patella 120 has been moved to an offset position and prior toinitiating any cuts on the bones in the patient's leg 70.

After cuts have been made on the distal end portion 124 of the femur 126and the proximal end portion 212 of the tibia 214 in the mannerpreviously explained, the lower portion 68 of the patient's leg can bemoved relative to the upper portion 72 of the patient's leg. The imagesprovided on the video screen 364 will enable a surgeon to betterunderstand the relationship between the femur, tibia, and ligaments inthe patient's leg during preliminary checking of ligament balancingafter the distal end portion 124 of the femur 126 has been cut and afterthe proximal end portion 212 of the tibia 214 has been cut.

During trials when trial tibial and femoral components have beentemporarily connected with the femur 126 and tibia 214, the imagesprovided at the video screen 364 will enable the surgeon to betterevaluate the interaction between the trial components and body tissue inthe knee portion 76 of the patient's leg 70. Once the trials have beencompleted and the femoral and tibial implants 286, 290 and 294positioned on the femur 126 and tibia 214, the images provided at thevideo screen 364 will enable the surgeon to evaluate the relationshipbetween the femoral and tibial implants.

During ligamentous balancing, images provided at the video screen 364will indicate to the surgeon whether or not there is any undesiredrelative movement between the femoral and tibial implants. It iscontemplated that the images be transmitted from the control unit 362 tothe video screen 364 during movement of the lower portion 68 of thepatient's leg 70 in any one or a combination of the directions indicatedby the arrows 256, 258, 259 and 260 in FIG. 25. Once the surgeon, withthe assistance of images provided at the video screen 364, is satisfiedthat the femoral and tibial implants 286, 290 and 294 have beencorrectly positioned in the knee portion 76 of the patient's leg 70, theincision 114 is closed.

The general construction and mode of operation of the C-arm fluoroscope360 (FIG. 34) and control unit 362 is the same as is disclosed in U.S.Pat. Nos. 5,099,859; 5,772,594; 6,118,845 and/or 6,198,794. However, itis contemplated that other known image generating devices could beutilized in place of the fluoroscope if desired. For example, an imagegenerating device similar to a magnetic resonance imaging unit (MRI)could be utilized.

In accordance with still another feature of the invention, a robot 370(FIG. 34) is provided to perform cutting and/or implant placementoperations on the knee portion 76 in the leg 70 of a patient. The robot370 includes a base 372. A support column 374 is moveable verticallyrelative to the base 372, in a manner indicated by arrows 376 in FIG.34. In addition, the support column 374 is rotatable about coincidentlongitudinal central axes of the base 372 and support column in a mannerindicated schematically by arrows 378 in FIG. 32. A main arm 382 ispivotally attached to an upper end portion of the support column 374.Motors and controls 386 are connected with the main arm 382. The mainarm is pivotal relative to the support column 374 in the mannerindicated by arrows 388 in FIG. 34.

A secondary arm 390 is pivotally mounted on an outer end portion of themain arm 382. The secondary arm 390 is pivotal relative to the main arm382 in the manner indicated by arrows 392. A mounting section 396 isrotatable about a longitudinal central axis of the secondary arm 390 andhas a mounting flange which is rotatable about an axis which extendsperpendicular to the longitudinal central axis of the secondary arm 390.

It is contemplated that a cutting tool, such as the saw 172, may bemounted on the mounting section 396. Controls for the robot 370 effectmovement of the saw relative to the distal end portion 124 of the femur126 to form the anterior cut surface 182 on the femur and to form adistal end cut on the femur. In addition, the robot 370 moves the saw toform chamfer cuts on the distal end portion 124 of the femur 126.

The robot 370 may also be utilized to move the saw to make the cuts toform the proximal end portion 212 of the tibia 214. Thus, the robot maybe utilized to form the proximal tibial cut surface 246 (FIG. 22).

By using the robot 370 to move the saw to form the cuts on the distalend portion 124 of the femur 126 and on the proximal end portion 212 ofthe tibia 214, the need for instrumentation, such as the femoralalignment guide 134 and anterior resection guide 138 of FIG. 11, thedistal resection guide 186 of FIGS. 16 and 18, and the tibial resectionguide 218, is eliminated. Controls for the robot 370 are connected withthe C-arm fluoroscope 360 to enable the position of the saw relative tothe femur and tibia to be viewed by the surgeon during an operation.

The robot 370 may have any one of many different constructions.Specifically, it is contemplated that the robot 370 may have the sameconstruction as is disclosed in U.S. Pat. No. 5,154,717. Alternatively,the robot 370 could have the construction disclosed in U.S. patentapplication Ser. No. 09/789,621 filed Feb. 21, 2001 by Peter M. Bonutti.However, it should be understood that other known robots could beutilized if desired. For example, a robot similar to the known “RoboDoc”™ could be utilized.

It is contemplated that a computer navigation system may be used withthe robot 370 to guide movement of a cutting tool, such as a saw ormilling cutter, relative to the tibia and femur in the leg 70 of thepatient. Two or more locating devices are connected with the distal endportion 124 of the femur 126. In addition, two or more locating devicesare connected to the proximal end portion of the tibia 214. The locatingdevices cooperate with motors and computer controls 386 for the robot370 to provide the robot with information as to the position of themounting section 396 and cutting tool relative to the femur 126 andtibia 214.

The locating devices may be of the reflective or energy emitting type orenergy receiving type. For example, three reflectors may be pinned ontothe distal end portion 124 of the femur 126. Similarly, three reflectorsmay be pinned onto the proximal end portion 212 of the tibia 214. Lighttransmitted from the robot 370 to the reflectors on the femur and tibiais reflected back to photo cells on the robot to enable the robot todetermine the positions of the femur and tibia. Rather than usingreflectors, energy emitting devices may be pinned onto the femur 126 andtibia 214. The energy emitting devices may emit either light or radiowaves.

The above-described image guided surgery system is merely intended to berepresentative of the type of system that can be used with the presentinvention.

However, it should be understood that other known image guided surgerysystems, both in conjunction and independent of robotic systems, couldbe utilized if desired. Examples of commercially available systemsinclude systems the Z-KAT (Hollywood, Fla.) suites, the MEDIVISIONsystem (Oberdorf, Switzerland), the STEALTH NAVIGATOR system(Louisville, Colo.), and the ORTHOPILOT System (Tuttlingen, Germany).

It should also be understood that the robot 370 could have any one ofmany different constructions. It is also contemplated that the robot 370could interact with a surgeon and patient in many different ways. Forexample, the robot could have a plurality of articulate arms which arecontrolled by the surgeon. Images provided by the fluoroscope 360 wouldenable the surgeon to control the articulate arms. Locating devicesconnected with the femur and tibia are visible to the surgeon in imagesprovided by the fluoroscope 360. Computer controls which respond to thelocating devices provide information to the surgeon about cutting toolsand/or other instruments being moved by the articulate arms. The surgeonoperated controls, the articulate arms, and the fluoroscope or otherimaging device may cooperate in the manner disclosed in U.S. Pat. Nos.6,063,095 and 6,102,850 if desired.

It is believed that it may be desired to use a hologram to provide athree-dimensional optical image of cuts to be made. Thethree-dimensional image would be projected onto the end portion 124 ofthe femur 126 and/or onto the end portion 212 of the tibia 214. Thethree-dimensional image may be lines indicating where the femur 126and/or tibia 214 are to be cut.

The three dimensional image would allow a surgeon 106 to visuallymonitor operation of the robot 370 during the making of cuts. If therewas even a small discrepancy, the surgeon 106 could interrupt operationof the robot and take corrective action. It is believed that theprojecting of a three-dimensional image onto surfaces to be cut will beparticularly advantageous when a robotic system which has surgeonoperated articulate arms is utilized. The projection of a hologramgenerated three-dimensional image would enable a surgeon to visuallydetermine whether or not a robotic system, similar to the systemdisclosed in U.S. Pat. No. 6,063,095 or 6,102,850, is being operatedproperly.

Patellar Resection

In the foregoing description, the patella 120 was everted or flippedfrom its normal position to a position in which an inner side 122 of thepatella faces outward (FIG. 7). The patella 120 was then cut while itwas in the everted position. A patellar implant was then mounted on thepatella 120 in a known manner. The patella 120 was then returned to itsnormal position with the inner side of the patella facing inward towardthe distal end portion 124 of the femur 126. This is a well known mannerof performing surgery on a patella to install a patellar implant.

In accordance with one of the features of the present invention and asdiscussed above, it is contemplated that the patella 120 will be cut andan implant positioned on the patella while the patella remains in asubstantially normal position relative to the femur 126. When thepatella 120 is in its normal position relative to the femur 126 (FIG.35), an inner side 122 of the patella 120 is disposed adjacent to thedistal end portion 124 of the femur 126. The patella 120 is urged towardthe trochlear groove 452 in the distal end portion 124 of the femur 126by the patellar tendon 456 and the patellar ligament 458. The patellartendon 456 connects the patella 120 with the quadriceps femoris muscle.The patellar ligament 458 connects the patella 120 with the tibia 214.The patellar tendon 456 and patellar ligament 458 may be referred to asfibrous connective tissue.

While the patella 120 is in the normal position illustrated in FIG. 35,a guide assembly 464 (FIG. 36) is positioned relative to the patella.The guide assembly 464 includes a main section 466 (FIG. 36) with a slot468 having guide surfaces along which a blade 170 of a saw 172 is moved.The main section 466 of the guide assembly 464 is positioned relative tothe patella 120 by a pair of parallel arms 474 and 476.

The arm 474 extends through the medially offset incision 114 and underthe superior aspect 480 of the in situ patella 120. The arm 476 extendsthrough the incision 114 and under the inferior aspect 482 of the insitu patella 120. By positioning the arm 474 under the upper end portion480 of the patella and the arm 476 under the lower end portion 482 ofthe patella 120, the guide surfaces in the slot 468 are accuratelyaligned with the patella 120 while the patella is in its normal positionrelative to the femur 126 and tibia 214 (FIG. 35).

While the in situ patella 120 is urged toward the distal end portion 124of the femur 126 by the patellar tendon 456 and the patellar ligament458 (fibrous connective tissue), the saw 170 or other cutting tool cutsalong a plane 484 (FIG. 35) to form a flat surface on the inside of thepatella 120. A relatively thin layer on which the inner side 122 of thepatella is disposed, is then removed from the patella 120. A patellarprosthesis or implant is then mounted on the cut surface on the insideof the patella while the patella remains in its normal position. Asuitable cement can be utilized to connect the implant with the patella.In addition, one or more projections may be provided on the inside ofthe implant to interconnect the implant and the patella in a knownmanner.

The guide assembly 464 can include inflatable bladders as an adjunct orreplacement for arms 474 and 476. These bladders would elevate thepatella 120 to obtain access to inner side 122. In this regard, U.S.Pat. No. 5,163,949 and progeny, such as U.S. Pat. Nos. 6,358,266 B1,6,277,136 B1, and 6,187,023 B1, discloses various embodiments ofretractors and method of dissecting tissue. These embodiments includefluid operated retractors, mechanical retractors, and combinationsthereof. The retractors and methods disclosed in this line of patents,which is incorporated herein by reference, can be used for patellaprocedures and/or visualization while the patella is maintained in asubstantially non-everted, anatomic position.

If desired, the patella 120 may be repaired before making cuts on thefemur 126 and tibia 214. Thus, immediately after making the incision114, the patella 120 may be cut while it is disposed in its normalposition. An implant may then be mounted on the patella 120. Thesurgically repaired patella 120 may then be moved to the offset positionof FIG. 8. The femoral and tibial cuts may then be made in the mannerpreviously explained in association with FIGS. 8-25 and the tibial andfemoral implants 286, 290 and 294 mounted on the femur 126 and tibia 214(FIGS. 27-29) while the previously repaired patella is in the offsetposition.

Extramedullary Tibial Instrumentation

When a tibial resection guide 500 (FIGS. 37 and 38) or the tibialresection guide 218 (FIG. 21) is to be positioned relative to theproximal end portion 212 of the tibia 214, an external tibial alignmentguide 504 (FIG. 37) may be used to position the tibial resection guiderelative to the tibia 214. The external tibial alignment guide 504 isdisposed outside of the patient's leg 70 and extends along the lowerportion 68 of the patient's leg. If desired, the patient's leg can be inthe position illustrated in FIGS. 2, 3, and 25.

The external tibial alignment guide 504 (FIG. 37) includes a hollowdistal shaft 508. A proximal shaft 510 is telescopically received in thedistal shaft 508. When the proximal shaft 510 has been extended for adesired distance from the distal shaft 508, a vertical adjustment knob514 is tightened to hold the proximal shaft 510 against movementrelative to the distal shaft 508.

The foot or lower end portion of the hollow distal shaft 508 isconnected with the mid-point between the palpable medial and lateralmalleoli by a spring clamp 518. The spring clamp 518 is aligned with thesecond metatarsal and grips the outside of the ankle portion 86 (FIG.25) of the patient's leg 70. The proximal shaft 510 (FIG. 37) of theexternal tibial alignment guide 504 is aligned with the medial third ofthe tibial tubercle. This results in the external tibial alignment guide504 being positioned along the outside of the patient's leg with thelongitudinal axis of the external tibial alignment guide 504 extendingparallel to a longitudinal central axis of the tibia 214.

A stylus 522 (FIG. 38) is mounted on the tibial resection guide 500. Thestylus 522 engages the proximal end portion 212 of the tibia to positionthe tibial resection guide 500 relative to the tibia. The tibialresection guide 500 is connected to the proximal end portion 212 of thetibia by a single pin 524 (FIG. 38) which extends through the tibialresection guide 500 into engagement with the proximal end portion 212 ofthe tibia 214. The external tibial alignment guide 504 and the stylus522 cooperate with the tibial resection guide 500 and pin 524 to holdthe tibial resection guide against rotation.

Although the tibial resection guide 500 has been shown in FIG. 38 asbeing connected directly to the proximal end portion 212 of the tibia214, the tibial resection guide could be connected with proximal endportion 212 of the tibia 214 in different manner. Thus, in FIG. 38, theposterior facing side of the tibial resection guide 500 is disposed inabutting engagement with the proximal end portion 212 of the tibia 214.However, the posterior facing side of the tibial resection guide 500could be positioned in engagement with skin which encloses the proximalend portion 212 of the tibia 214 in order to minimize the overall lengthof the incision 114. This would result in the pin 524 extending throughthe tibial resection guide and through the skin and other tissueoverlying the proximal end portion 212 of the tibia 214 into engagementwith the proximal end portion of the tibia. The manner in which thetibial resection guide would be mounted on the tibia, would be similarto that disclosed in FIG. 31 for the distal resection guide 186.However, the tibial resection guide 500 is secured in place by a singlepin 524, by the external tibial alignment guide 504, and, to some extentat least, the stylus 522.

The tibial resection guide 500 is medially offset from the externaltibial alignment guide 504. This is because the incision 114 (FIG. 6) isdisposed adjacent to the medial edge portion of the patella 120. Ifdesired, the incision 114 could be disposed adjacent to the lateral sideof the patella 120. If this was done, the tibial resection guide 500would be laterally offset from the external tibial alignment guide 504.Regardless of which direction the tibial resection guide 500 is offset,a portion of the tibial resection guide may be disposed beneath bodytissue to minimize the size of the incision 114.

In accordance with a feature of the apparatus of FIGS. 37 and 38, theexternal tibial alignment guide 504 is maintained in position on thetibia 214 during cutting of the proximal end portion 212 of the tibia214 in a manner similar to that illustrated in FIG. 21. Maintaining thetibial alignment guide 504 in place during cutting of the proximal endportion 212 of the tibia 214, enables the tibial alignment guide to beutilized to position the tibial resection guide 500 relative to thetibia 214. This enables the tibial resection guide 500 to be connectedto the tibia 214 by only the single pin 524. In the past, a plurality ofpins have been utilized to connect the tibial resection guide 500 withthe tibia 214 in a manner similar to the disclosures in U.S. Pat. Nos.5,234,433 and 5,643,272. It should be understood that the tibialalignment guide 504 and a tibial resection guide, similar to the tibialresection guide 500, may be utilized during performance of a partialknee replacement in the manner disclosed in the aforementioned U.S. Pat.No. 5,234,433.

Since, the external tibial alignment guide 504 is maintained in positionduring cutting of the tibia, the saw blade 170 or other cutting toolmust be angled around the proximal shaft 510 of the external tibialalignment guide 504 as the proximal end portion 212 of the tibia 214 iscut. During movement of the saw blade 170 (FIGS. 13 and 21) along theguide surface 530 (FIG. 38), only an initial portion of the cut in theproximal end portion 212 of the tibia is made. This is because theproximal shaft 510 of the external tibial alignment guide 504 partiallyblocks the saw blade 170. In addition, the tibial resection guide 500 isdown sized.

Opposite ends 534 and 536 of the tibial resection guide 500 are spaceapart by a distance less than two thirds (⅔) of the distance betweentips of lateral and medial epicondyles 236 and 238 (FIG. 38) on theproximal end portion 212 of the tibia 214. Therefore, after an initialportion of the cut across the proximal end portion 212 of the tibia 214has been made while moving the saw blade 170 along the guide surface530, the tibial resection guide 500 and external tibial alignment guide504 are disconnected from the tibia 214. The tibial cut is thencompleted.

During completion of the tibial cut, the guide surface 530 on theresection guide 500 is not in position to guide the saw blade 170.Therefore, cut surfaces fanned during the making of the initial portionsof the tibial cut are utilized to guide the saw blade. When the tibialcut is to be completed the saw blade 170 is inserted into a slot or kerfformed in the distal end portion 212 of the tibia 214 by the saw blade170 as it moved along the guide surface 530 and made the initial portionof the tibial cut. During completion of the tibial cut, the cut surfaceswhich were formed on the proximal end portion 212 of the tibia 214during the initial portion of the tibial cut are used to guide movementof the saw blade.

The tibial resection guide 218 of FIG. 21 has a guide surface 242 formedby a closed ended slot. The tibial resection guide 500 of FIG. 38 has aguide surface 530 formed by an open ended slot. Thus, the tibialresection guide 500 includes a slot 540 which has an open end 542. Theopen end 542 of the slot 540 facilitates movement of the saw blade 170along the slot and angling of the saw blade relative to the slot tomaximize the extent of the initial portion of the tibial cut. Thus, theextent of the tibial cut formed during movement of the saw blade alongthe guide surface 530 on the tibial resection guide 500 is maximized byforming the slot 540 with the open end 542 so that the saw blade can beangled at the open end 542 of the slot.

The tibial resection guide 500 may be used with a first cutting toolduring making of the initial portion of the tibial cut. A second cuttingtool may be used to complete the tibial cut. For example, a relativelysmall blade 170 of an oscillating saw 172 may be used to make theinitial portion of the tibial cut. A relatively long blade of areciprocating saw may be used to complete the tibial cut. If desired, achisel and/or milling cutter could be used to make the initial portionand/or final portion of the tibial cut.

It is contemplated that it may be desired to set the tibial resectionguide 500 (FIG. 37) for any one of a plurality of different resectionlevels. Thus, the tibial resection guide 500 could be set to make atibial cut at a distance of two millimeters from a location on theproximal end portion 212 of the tibia 214 which is engaged by the stylus522. Alternatively, the tibial resection guide 500 could be utilized tomake a cut at a distance of eight millimeters from the location wherethe stylus 522 engages the proximal end portion 212 of the tibia 214. Ofcourse, the greater the distance at which the tibial cut is made fromthe location where the stylus 522 engages the proximal end portion 212of the tibia 214, the greater will be the thickness of a layer of boneremoved from the distal end portion 212 of the tibia 214.

To facilitate movement of the tibial resection guide 500 between variousdepths, the stylus 522 includes a drive assembly 548 (FIG. 38). Thedrive assembly 548 is actuated by rotating a knob 550 on the stylus.Rotation of the knob 550 through a predetermined distance, that is, onecomplete revolution, will cause the drive assembly 548 to move thetibial resection guide 500 for a predetermined distance along theproximal shaft 510 of the external tibial alignment guide 504. Thus,rotation of the knob 550 for one complete revolution in a clockwisedirection, viewed from above, is effective to move the tibial resectionguide 500 through a distance of two millimeters downwards along theproximal shaft 510 of the external tibial alignment guide. Of course,this would increase the depth of the tibial cut by a distance of twomillimeters. Similarly, rotating the knob 550 through two completerevolutions is effective to actuate the drive assembly 548 to move thetibial resection guide 500 downward (as viewed in FIG. 39) along theproximal shaft 510 of the external tibial alignment guide 504 through adistance of four millimeters.

The drive assembly 548 includes an externally threaded member which isconnected with the knob 550. An internally threaded member is connectedwith the tibial resection guide 500. The internally threaded memberengages the externally threaded member and is held against axial androtational movement relative to the tibial resection guide 500.

After the tibial resection guide 500 has been moved to a desiredposition relative to the proximal end portion 212 of the tibia 214, alocking knob 556 is rotated to actuate a lock screw to hold the tibialresection guide 500 against movement along the proximal shaft 510 of theexternal tibial alignment guide 504. The pin 524 is then insertedthrough the tibial resection guide 500 into the proximal end portion 212of the tibia 214.

Rather than moving the tibial resection guide 500 along the proximalshaft 510 of the external alignment guide 504 under the influence offorce transmitted from the knob 550 through the drive assembly 548 tothe tibial resection guide, the drive assembly could be connected withthe knob 556. For example, the knob 556 could be connected with a piniongear of a rack and pinion drive arrangement. The rack portion of thedrive arrangement could be mounted on the proximal shaft 510. If thiswas done, rotation of the knob 556 would cause the rack and pinion gearset to move the tibial resection guide along the proximal shaft 510through a distance which is a function of the extent of rotation of theknob 556. The stylus 552 would be connected to the tibial resectionguide 500 and would engage the proximal end of the tibia 214 to indicatewhen the tibial resection guide 500 had moved to a desired positionrelative to proximal end portion 212 of the tibia.

It is contemplated that the stylus 522 could be eliminated if desired.The tibial resection guide 500 could be positioned by sliding a thinmember, such as a blade, beneath tissue overlying the proximal endportion 212 of the femur 214. A reference surface on the tibialresection guide 500 would then be moved into engagement with the bladeor other thin member. The reference surface may be disposed on the upper(as viewed in FIG. 38) end of the tibial resection guide 500 or may bedisposed in a slot in the tibial resection guide. The reference surfacemay also be utilized to guide movement of a saw or other cutting tool.

If desired a hook or sickle shaped locating member could be extendedfrom the tibial resection guide 500 to position the tibial resectionguide relative to the proximal end portion 212 of the tibia 214. Whenthe incision 114 and tibial resection guide 500 are medially offsetrelative to the tibia 214, the locating member would extend along themedial side of the proximal end portion 212 of the tibia. This wouldenable the stylus 522 to be eliminated.

It is contemplated that retractors may be mounted on the proximal shaft510 of the external tibial alignment guide 504. The retractors engageopposite sides of the incision. The retractors are effective to expandthe incision 114 and/or maintain the incision in a desired positionrelative to the proximal end portion 212 of the tibia 214.

Cannula

In accordance with another feature of the invention, access to theinterior of the knee portion 76 of the leg 70 may be obtained through acannula 564 (FIG. 39). The cannula 564 is inserted into the incision114. If desired, the patient's leg 70 can be in the position shown inFIGS. 2, 3 and 25. The upper portion of the patient's leg is supportedby the leg support 80.

The incision 114 is formed with a relatively short length in the mannerpreviously described herein. The cannula 564 has an initial size,illustrated in FIG. 39, which stretches the viscoelastic material oftissues forming the knee portion 76 of the leg 70. Therefore, initialinsertion of the cannula 564 into the incision 114 is effective toexpand the incision.

Compact cutting tools, similar to those utilized for arthroscopic,endoscopic, or fiber optic assisted surgery may be at least partiallymoved through a passage 566 (FIG. 39) formed by an inner side 568 of thecannula 564. The cutting tools may have a construction similar to theconstruction illustrated in U.S. Pat. No. 5,540,695 or 5,609,603.Alternatively, the cutting tools may have a construction similar to theconstruction disclosed in U.S. patent application Ser. No. 09/483,676filed Jan. 14, 2000 by Peter M. Bonutti and having a disclosure whichcorresponds to U.S. Pat. No. 5,269,785.

The cannula 564 is advantageously expandable to further stretch theviscoelastic tissue of the knee portion 76. Of course, expanding thecannula 564 increases the size of the passage 566 to enable a relativelylarge object to pass through the passage. Thus, the cannula 564 may beexpanded to facilitate movement of the implants 286, 290 and 294 throughthe cannula. The leg 70 is in the position shown in FIGS. 2, 3 and 24during expansion of the cannula and movement of objects through thepassage 566.

It is contemplated that the expandable cannula 564 may have manydifferent known constructions. The illustrated cannula 564 is formed ofelastomeric material and has the same construction as is disclosed inU.S. patent application Ser. No. 08/470,142 filed Jun. 6, 1995 by PeterM. Bonutti, et al. and having a disclosure which corresponds to thedisclosure in U.S. Pat. No. 5,961,499. It should be understood that thecannula 564 could have a different construction, for example, aconstruction similar to the constructions disclosed in U.S. Pat. No.3,811,449 or 5,183,464.

The cannula 564 can be expanded in many different ways other than underthe influence of force transmitted directly to the cannula from anobject moving through the cannula. For example, the cannula may beexpanded by force transmitted from an implant 286, 290 and/or 294 to thecannula. The cannula 564 may be expanded by inserting tubular membersinto the cannula. Alternatively, fluid pressure could be used to expandthe cannula 564 in the manner disclosed in the aforementioned Bonutti,et al. patent application Ser. No. 08/470,142 filed Jun. 6, 1995.

Rather than being expanded by inserting the expandable cannula 564 intothe incision 114, the incision may be expanded by utilizing pneumaticretractors. The pneumatic retractors may have a construction similar tothe construction disclosed in U.S. Pat. No. 5,163,949. By utilizing theexpandable cannula 564 or the expandable pneumatic retractors, force canbe applied against opposite sides of the incision 114 to stretch theviscoelastic material disposed adjacent to opposite sides of theincision. This will result in the relatively small incision 114 beingexpanded to accommodate relatively large surgical instruments and/orimplants.

Although a single incision 114 is illustrated in FIG. 39, it iscontemplated that a plurality of incisions could be provided. Thus, asmall incision may be spaced from the incision 114 to enable a cuttingtool to be moved into the knee portion 76 along a path which is spacedfrom and may be transverse to a path along which a cutting tool is movedthrough the incision 114. A second cannula, which is smaller than thecannula 564, may be utilized with the second incision.

Implant with Interconnectable Portions

In order to enable surgery on a knee portion 76 of a patient's leg 70 tobe conducted through an incision 114 of relatively small size, theimplant may advantageously be formed in two or more portions (FIG. 40).The portions of the implant are sequentially moved through the incision114 into engagement with the distal end portion 124 of the femur 126and/or the proximal end portion 212 of the tibia 214. It is believedthat having the implant formed as two or more portions will facilitatemovement of the implant through the cannula 564 (FIG. 39).

As the portions of the implant are sequentially moved through theincision 114, they are positioned in engagement with one or more of thebones, that is, the femur 126 and/or the tibia 214 in the leg 70 of apatient. After the plurality of portions of the implant have been movedthrough the incision 114 and positioned in engagement with the femur 126and/or tibia 214, the portions of the implant are interconnected to forma unitary implant. If desired, the portions of the implant are movedthrough the incision 114 and interconnected while the leg of the patientis in the position illustrated in FIGS. 2, 3 and 25.

It is contemplated that the portions of the implant may beinterconnected, while they are disposed in the patient's body and inengagement with either the femur 126 and/or tibia 214, in many differentways. For example, the portions of the implant may be bonded together toform a one piece implant. The portions of the implant may be bondedtogether by the application of energy in anyone of many different formsto a joint between portions of the implant. For example, ultrasonicenergy could be applied to the implant. Alternatively, heat could bedirectly applied to the implant. If desired, a laser could be utilizedto effect bonding of separate portions of the implant together.

It is also contemplated that the separate portions of the implant couldbe mechanically interconnected. This could be done with a fastener whichextends between portions of the implant. Alternatively, a retainermember such as a rod or bar could extend between portions of theimplant. Regardless of how the portions of the implant areinterconnected, the portions of the implant are interconnected afterthey have been moved into the patient's body.

In the embodiment of the invention illustrated in FIG. 40, the femoralcomponent 290 of an implant is formed as two separate portions 572 and574. The portion 572 of the implant 290 is moved through the incision114 into engagement with the distal end portion 124 of the femur 126.Thereafter, the portion 574 of the implant 290 is moved through theincision 114 into engagement with the distal end portion 124 of thefemur 126. After the two portions 572 and 574 of the femoral component290 of the implant have been positioned in abutting engagement with thefemur 126, the two portions of the implant are interconnected at a joint576 between the two portions of the implant. If desired, the portions572 and 574 of the femoral component 290 of the implant may be movedthrough the cannula 564 of FIG. 39.

The specific implant 290 illustrated in FIG. 40 has portions formed of apolymeric material which may be either a polymer or a co-polymer. Thematerial of the two portions 572 and 574 of the implant 290 are heatedat the joint 576 while the two portions of the implant are disposed inthe patient's body in engagement with the femur 126. As this occurs, thematerial forming the two portions 572 and 574 of the implant 290 isheated to a temperature within its transition temperature range andbecomes tacky without changing its overall configuration. The twoportions 572 and 574 of the implant 290 may be heated by the direct orindirect application of heat. The indirect application of heat mayinclude applying ultrasonic energy to the implant.

The heated material of the two portions 572 and 574 of the implant 290are then pressed together at the joint 576 to form a bond between thetwo portions of the implant. As this occurs, there is a fusing of thematerial of the portion 572 of the implant 290 with the material 574 ofthe implant. This fusing together of the two portions 572 and 574 occurin the patient's body and results in the formation of a one-pieceunitary implant 290.

Rather than being formed of a polymeric material, it is contemplatedthat the two portions 572 and 574 of the implant could be formed ofmetal and have a polymeric layer on a side of the metal toward the femur126. This would result in the layer of polymeric material being disposedin engagement with the distal end portion 124 of the femur 126 and themetal forming the femoral component 290 facing toward the tibia 214 forengagement with the tibial bearing insert 294 (FIG. 32). With such aconstruction, the application of energy to the two portions 572 and 574of the implant would result in a heating of the layer of polymericmaterial on the inside of the layer of metal. The heated polymericmaterials on the two portions 572 and 574 bond together at the joint 576in a manner previously described.

When the two portions 572 and 574 of the femoral implant 290 are to beinterconnected by fusing together sections of polymeric material whichform the portions 572 and 574 of the implant or sections of polymericmaterial which are disposed on layers of metal forming part of theportions 572 and 574 of the implant 290 to be interconnected, it iscontemplated that they may be interconnected in many different ways. Oneway in which polymeric material on the portions 572 and 574 of thefemoral implant 290 may be interconnected is the same as is disclosed inU.S. patent application Ser. No. 09/737,380 filed Dec. 15, 2000 by PeterM. Bonutti, et al. This patent application contains a disclosure whichcorresponds to the disclosure in U.S. Pat. No. 6,059,817.

The two portions 572 and 574 of the implant 290 (FIG. 40) may be formedof only metal. If this is done, the two portions 572 and 574 of theimplant may be mechanically interconnected. For example, a screw couldextend from the portion 574 of the implant 270 to the portion 572 of theimplant while the two implants are in engagement with the distal endportion 124 of the femur 126. Alternatively, a snap type joint 576 couldbe provided between the portions 572 and 574 of the implant. Althoughthe two portions 572 and 574 of the implant 290 are positioned inengagement with the femur 126 and interconnected while the leg 70 of thepatient is in the position illustrated in FIGS. 2, 3 and 25, the twoportions of the implant could be positioned in engagement with the femur126 while the leg 70 is straight (extended).

The implant 290 is connected with the femur 126. However, it iscontemplated that a tibial implant could be formed as a plurality ofseparate portions which are interconnected when they are in the kneeportion 76 of the patient's leg 70. It should be understood that theimplant 290 could be formed of more than two portions. For example theimplant could be formed with four separate portions which areinterconnected in the patient's body. Although the implant 290 is to beused in a knee portion of a patient's body, it is contemplated thatimplants used at other portions of a patient's body could beinterconnected in the patient's body.

In the embodiment of the invention illustrated in FIG. 40, the separateportions 572 and 574 of the implant 290 are positioned in engagementwith the same bone, that is, femur 126 and interconnected. However, itis contemplated that one position of an implant could be positioned inengagement with a first bone and another portion of the implantpositioned in engagement with a second bone. However, the two portionsof the implant would be interconnected in the patient's body. The twoportions of the implant may be interconnected after they have beenpositioned in engagement with bones in the patient's body.Alternatively, the two portions of the implant could be interconnectedin the patient's body, before one or both portions of the implant havebeen positioned in engagement with a bone.

For example, a first component of an implant may be connected with afemur 126 in a patient's body. A second component may be connected witha tibia 214 in the patient's body. The two components areinterconnected, in the patient's body, after they have been connectedwith the femur and tibia.

Transducer for Ligament Balancing

After the femoral component 290 and tibial components 286 and 294 of theimplant had been positioned in the knee portion 76 of the patient's leg70, the ligaments are balanced in flexion, extension, and rotation inthe manner previously described. It should be understood that eventhough the implants have not been shown in FIGS. 41 and 42, ligamentbalancing may be undertaken before and/or after the implants beenpositioned in engagement with the femur 126 and tibia 214. However, itis contemplated that ligament balancing could be undertaken duringsurgical procedures which do not require cutting of the femur 126 andtibia 214 and/or implants.

In accordance with one of the features of the invention, during ligamentbalancing, tension forces in fibrous connective tissue such ascollateral ligaments 590 and 592 (FIGS. 41 and 42) are compared. If theforces in one of the ligaments 590 or 592 are excessive, the ligament inwhich the excessive force is present may be released. Similarly, if oneof the ligaments is too loose, the ligament may be tightened.

In accordance with another one of the features of the invention,transducers are positioned between one or more bones in the knee portion76 of the leg 70 of the patient. The transducers enable tension forcesin ligaments 590 and 592 to be compared. The transducers may be used todetermine the magnitude of the tension forces in the ligaments 590 and592.

Thus, a first or lateral transducer 596 (FIGS. 41 and 42) is positionedbetween a lateral side of the distal end portion 124 of the femur 126and a lateral side of the proximal end portion 212 of the tibia 214.Similarly, a second or medial transducer 598 is positioned between amedial side of the distal end portion 124 of the femur 126 and a medialside of the proximal end portion of the tibia 214. The transducers 596and 598 are connected with a computer 600 (FIG. 41) or other processor.

The computer 600 (FIG. 41) has a display area 601 at which the outputfrom the lateral transducer 596 is displayed. Similarly, the computer600 has a display area 602 at which the output from the medialtransducer 598 is displayed. By comparing the outputs at the displayareas 601 and 602, a surgeon can determine the relationship between thetension in the ligament 590 and the tension in the ligament 592. Inaddition, the surgeon can determine the magnitude of the tension in theligaments 590 and 592.

It is contemplated that the leg 70 of the patient will be moved betweenthe flexed condition of FIGS. 2, 3, 25 and 41 and an extended positionor straight condition (FIGS. 4 and 42), while the output from thetransducers 596 and 598 is viewed at the display areas 601 and 602 ofthe computer 600. This will provide the surgeon with a clear indicationof the manner in which tension forces in the ligaments 590 and 592varies during bending of the knee portion 76 of the leg 70 of a patient.If an image generating device, similar to the C-arm fluoroscope 360 ofFIG. 34, is used in association with the transducers 596 and 598, thesurgeon can see how components of the knee joint are interacting as thetension in the ligaments varies.

In addition to checking the tension in the ligaments 590 and 592 duringmovement of the leg 70 of the patient between flexed and extendedconditions, it is contemplated that the tension in the ligaments 590 and592 will be compared during the application of rotational forces to thelower portion 68 of the knee of the patient. Thus, forces tending torotate the lower portion 68 of the leg of the patient in the directionof the arrow 258 in FIG. 25 are applied to the lower portion 68 of theleg 70. As these rotational forces are applied, the outputs from thetransducers 596 and 598 (FIG. 41) are displayed for review by a surgeonto determine whether or not the ligaments 590 and 592 are rotationallybalanced. The transducers 596 and 598 may be utilized to provide outputscorresponding to forces resulting from a combination offlexion/extension movement and rotational movement of the lower portion68 of the patient's leg 70. It should be understood that the transducers596 and 598 may be utilized throughout the entire ligament balancingprocess previously described herein in order to enable a surgeon tocompare tension forces in the ligaments 590 and 592 throughout theligament balancing process.

Although the transducers 596 and 598 have been illustrated schematicallyin FIGS. 41 and 42 as being associated with the end portions of thefemur 126 and tibia 214, it should be understood that the transducers596 and 598 could be associated with other joints if desired. Forexample, the transducers 596 and 598 could be positioned betweenvertebrae in a patient's spine. If this was done, the patient's spinecould be bent in either anterior or lateral flexion and extension. Theoutput at the display areas 601 and 602 would indicate the manner inwhich forces transmitted between the vertebrae vary during bending ofthe spine.

It is contemplated that the transducers 596 and 598 could have manydifferent constructions. However, in the illustrated embodiment of theinvention, the transducers 596 and 598 are pneumatic transducers. Thus,the lateral transducer 596 (FIG. 42) includes a container or bladderhaving a chamber which is filled with fluid. It is contemplated that thechamber could be filled with either a gas or a liquid. In the embodimentof the invention illustrated in FIGS. 41 and 42, the transducers 596 and598 have the same construction and are of pneumatic type. Therefore, thechamber is filled with air. However, the chamber could be filled with aliquid, for example, saline solution, if desired.

The transducers 596 and 598 are disposed between the femur 126 and thetibia 214. Although it should be understood that the femoral implant 290and tibial tray 286 and bearing 294 have not been illustrated in FIGS.41 and 42, the implants may or may not be present when the transducersare positioned between the femur 126 and tibia 214. Depending upon thelocation of the transducers 596 and 598 they may or may not be disposedin engagement with a portion of either the femoral or tibial implant.With a partial knee replacement, one of the transducers 596 or 598, isdisposed between femoral and tibial implants. The other transducer isdisposed between surfaces on the femur 126 and the tibia 214.

A conductor 604 is provided to transmit an output signal from thelateral transducer 596 to the computer display 601 (FIG. 42). Theconductor 604 could be constructed so as to conduct either fluidpressure from the transducer 596 to the computer 600 or to conduct anelectrical signal from a fluid pressure transducer exposed to the fluidpressure in the transducer 596. The medial transducer 598 is connectedwith the display 602 by a conductor 606.

It is contemplated that the transducers 596 and 598 could have manydifferent constructions including any one of the constructions disclosedin U.S. Pat. No. 5,667,520 or in U.S. patent application Ser. No.09/483,676 filed Jan. 14, 2000 by Peter M. Bonutti and having adisclosure corresponding to the disclosure in U.S. Pat. No. 5,269,785.The transducers 596 and 598 may be formed of a material which isbiodegradable or a material which is non-biodegradable.

Although the illustrated transducers 596 and 598 (FIGS. 41 and 42) areof the pneumatic type, it is contemplated that a different type oftransducer could be utilized if desired. For example, the transducers596 and 598 could be solid state devices, such as piezoelectric loadcells. Alternatively, the transducers could include deformable membersto which strain gauges are attached.

It should be understood that the transducers 596 and 598 could be usedto measure and/or compare tension in the ligaments 590 and 592immediately after making the incision 114. In addition or alternatively,the transducers 596 and 598 could be used to measure and/or comparetension in the ligaments 590 and 592 during trials with provisionalcomponents. Of course, the transducers 596 and 598 can be used tomeasure and/or compare tension in the ligaments after the implants 286,290 and 294 have been mounted in the knee portion 76.

In the embodiment of this invention illustrated in FIGS. 41 and 42, thetransducers 596 and 598 are disposed between end portions of the femur216 and tibia 214. Therefore, the transducers 596 and 598 onlyindirectly respond to variations in tension in the collateral ligaments590 and 592. It is contemplated that the transducers 596 and 598 couldbe positioned so as to directly respond to variations in the tension inthe collateral ligaments 590 and 592.

For example, the transducer 596 could be positioned between the ligament590 and lateral sides of the femur 126 and/or tibia 214. Similarly, thetransducer 598 could be positioned between the ligament 592 and medialsides of the femur 126 and/or tibia 214.

It is contemplated that transducers, similar to the transducers 596 and598, could be utilized to determine variations in tension in ligamentsand/or tendons other than the ligaments 590 and 592. For example,transducers could be utilized to determine the tension in the patellartendon 456 (FIG. 42) and/or the patellar ligament 458. If desired,transducers, similar to the transducers 596 and 598, could be positionedso as to respond to variations in tension in the posterior cruciateligament 250 and/or the anterior cruciate ligament. It is contemplatedthat a plurality of transducers, similar to the transducers 596 and 598,may be positioned so as to respond to variations in tension in variouscombinations of ligaments and/or tendons.

In addition to providing outputs which are a function of variations intension in ligaments and/or tendons, the transducers 596 and 598 may beutilized to apply force against the femur 126 and tibia 214. When thisis to be done, fluid under pressure is conducted to either or both ofthe transducers 596 and/or 598. An increase in fluid pressure conductedto the transducers 596 and 598 is effective to expand containers orbladders in the transducers.

The fluid pressure force applied against the transducers 596 and/or 598is transmitted to the femur 126 and tibia 214. This force may be used tostretch the collateral ligaments 590 and 592 and/or other body tissue.If it is desired to stretch one of the ligaments 590 or 592 to a greaterextent the other ligament, the fluid pressure transmitted to one of thetransducers 596 or 598 would be greater than the fluid pressuretransmitted to the other transducer. The force transmitted to the femur126 and tibia 214 is indicated at the displays 61 and 601.

It is contemplated that the transducers 596 and 598 will be removedbefore the limited incision 114 is closed. However, if it is desired,the transducers 596 and 598 may be left in place and utilized after theincision 114 is closed. When this is to be done, the transducers 596 and598 may advantageously be formed of biodegradable material. By leavingthe transducers 596 and 598 in place after the incision 114 is closed,the tension in the ligaments 590 and 592 may be compared during therapy.If desired, one or both ligaments 596 and/or 598 could be conductingfluid pressure to one or both transducers 596 and/or 598 during therapy.

Inlaid Implant—Femur

In the embodiment of the invention illustrated in FIGS. 8-28, articularsurfaces on the distal end portion 124 of the femur 126 and the proximalend portion 212 of the tibia 214 are cut away using a saw or othercutting tool. This results in areas on the distal end portion 124 of thefemur 126 and the proximal end portion 212 of the tibia 214, wherearticular surfaces were previously disposed, being cut to have a flatplanar configuration. Thus, an anterior skim cut, a distal end cut, andchamfer cuts are made on the distal end portion 124 of the femur 126while a proximal end cut is made on the proximal end portion 212 of thetibia 214. After the cuts have been made, the femoral implant extendsacross or encloses the cuts on the distal end portion 124 of the femur126 and the tibial implant extends across the cut on the tibial endportion 212 of the tibia 214.

It is contemplated that rather than enclosing the end portions of thefemur and tibia with implants, the implants could be inlaid into the endportion of the femur and/or tibia. When an implant is to be inlaid intothe distal end portion 124 of the femur 126 (FIG. 43), a recess 610 isformed in the distal end portion 124 of the femur 126. To form therecess 610, a cutting tool, such as a milling cutter 614 (FIG. 44), isutilized to cut away a defective portion of an articular surface on thedistal end portion 124 of the femur 126. The milling cutter 614 isrotated about its longitudinal central axis and has cutting edgesdisposed in a cylindrical array about the periphery of the millingcutter. The extent of the defective portion of the articular surfacedetermines the extent to which the milling cutter 614 cuts away thearticular surface.

A guide 620 (FIG. 44) is provided for the milling cutter or othercutting tool. The guide 620 is effective to limit the extent of axialmovement of the milling cutter 614 into the distal end portion 124 ofthe femur 126 to thereby limit the depth of the recess 610. The guide620 limits side wise, that is, radial movement of the milling cutter 614to an area corresponding to the desired configuration of the recess 610.This results in the recess 610 being fanned with a uniform depththroughout the extent of the recess and with a desired configuration.The construction of the guide 620 in the manner in which it cooperateswith the milling cutter 614 may be similar to that disclosed in U.S.Pat. Nos. 5,344,423; 5,769,855; and/or 5,860,981.

Once the recess 610 has been formed using the milling cutter 614 in themanner illustrated schematically in FIG. 44, an implant 626 (FIGS. 43and 45) is positioned in the recess. The implant 626 fills the recess610 and has an outer surface 628 (FIG. 45) which forms a continuation ofthe naturally occurring articular surface 616 formed by the distal endportion 124 of the femur 126. The outer surface 628 of the implant 626replaces defective articular surface area removed by the milling cutter614 from the distal end portion 124 of the femur 126.

The outer surface 628 on the implant 626 cooperates with an articularsurface on a tibia 214 in the same general manner as the originalarticular surface area removed by the milling cutter 614. Of course, theouter surface 628 of the implant 626 is free of defects that made itnecessary to replace the corresponding area on the articular surface 616of the distal end portion 124 of the femur 126. The outer surface 628 ofthe implant 626 may engage an articular surface formed by the boneymaterial of the tibia 214. Alternatively, the outer surface 628 of theimplant 626 may engage the surface of an implant disposed on the tibia214.

During recovery of the patient, the naturally occurring surface 616 onthe femur 126 and the implant 626 may both be load bearing. By havingthe implant 626 surrounded by load bearing natural bone, the implant isheld in place on the distal end portion 124 of the femur 26. Inaddition, the magnitude of the load which must be transmitted throughthe implant 626 is minimized.

The implant 626 could have any desired construction. Thus, the implantcould be formed of a polymeric material or it could be formed of ametallic material. However, in accordance with one of the features ofthe invention, the implant 626 is formed of a material which promotesbiological resurfacing and the growth of bone from the distal endportion 124 of the femur 126 into the implant to fill the recess 610with new bone growth. The implant 626 may also be at least partiallyformed of material which promotes the growth of cartilage or othertissue over the implant.

The implant 626 may be formed with a non-living three dimensionalscaffold or framework structure on which bone growth promotingmaterials, such as bone morphogenetic proteins, are disposed. The threedimensional framework or platform on which the bone growth promotingmaterials are disposed may be formed of either a biodegradable or anon-biodegradable material. When the scaffold or framework structure isformed of a non-biodegradable material, the bone from the distal endportion 124 will grow through the scaffold so that the scaffold becomesembedded in new bone growth. The scaffold may be formed of a porousmetal or ceramic material. When the scaffold is formed of abio-degradable material, the scaffold will eventually degrade and beabsorbed by body tissue.

The scaffold may be formed of a mesh or a felt-like material, or aporous material similar to coral. The scaffold forms a growth supportingmatrix to support cellular migration from the boney material of thedistal end portion 124 of the femur 126 into the implant 626. If thescaffold or platform is made of a bio-degradable material, then thescaffold or platform degrades and disappears after a period of time. Itis contemplated that the scaffold could be formed of a bio-degradablematerial such as polyglycolic acid or polylactic acid. If desired, thescaffold or framework could be formed of fibrous connective materialssuch as portions of ligaments, tendons and/or bones obtained from humanand/or animal sources. The scaffold could be formed of collagen. Thescaffold may be formed of submucosal tissue.

The scaffold holds bone growth inducing materials and may include bonefragments to which tri-calcium phosphate, an antibiotic,hydroxyapatiate, allografts, autografts, and/or any other polymeric hasbeen added. It is believed that it will be particularly advantageous toprovide a bone growth morphogenetics protein in the implant 626 topromote the growth of bone into the implant. The scaffold may holdcultured and/or noncultured cells which promote biological resurfacing.

The matrix or scaffold for the implant 626 may contain tissue inductivefactors and/or cells. The cells may be mesenchymal cells which areintroduced into the scaffold in the operating room. Thus, the matrix orscaffold may be either biodegradable or non-biodegradable and may beconstructed at a location remote from an operation. After the scaffoldhas been transported to the operating room the mesenchymal cells may beintroduced into the scaffold.

It is contemplated that the matrix or scaffold for the implant 626 maycontain stem cells and/or fetal cells. The stem cells and/or fetal cellsmay be introduced into either a biodegradable or non-biodegradablematrix or scaffold in the operating room. It is contemplated that tissueinductive factors may be provided in the matrix or scaffold along withany desired type of precursor cells.

The matrix or scaffold for the implant 626 may contain osteoinductivematerials. The implant 626 may contain osteoblasts or osteoclast cellsor their precursors. The implant 626 may also contain platelet matrixcentrifuged from blood in a manner similar to that described in U.S.patent application Ser. No. 09/483,676, filed Jan. 14, 2000 by Peter M.Bonutti.

The matrix or scaffold for the implant 626 may be formed of allograftbone or collagen. Cartilage may be used to form the scaffold or matrix.The scaffold or matrix for the implant 626 may have a layeredconstruction with the layers being formed of different materials. Eachof the layers of the scaffold or matrix forming the implant 626 may beimpregnated with a different material. For example, precursor cells maybe provided in one layer and bone morphogenetic protein may be providedin another layer.

It is contemplated that submucosal tissue may be used to form thescaffold for one or more of the layers of the implant 626. Thesubmucosal tissue may be prepared in a manner similar to the mannerdisclosed in U.S. Pat. No. 5,755,791. The various layers of the implant626 may be assembled in the operating room.

The implant 626 may be formed of multiple tissue fragments. Thus, atissue press, similar to the tissue presses disclosed in U.S. patentapplication Ser. No. 09/602,743 filed Jun. 23, 2000, by Peter M. Bonuttiand having a disclosure which corresponds to the disclosure in U.S. Pat.No. 5,662,710 may be utilized to shape the implant to a desiredconfiguration.

The implant 626 may be formed to have any one of a plurality ofdifferent sizes and configurations. The implant may be shaped to thedesired configuration at a location remote from an operating room andtransported to the operating room. Alternatively, the implant 626 couldbe cut to the desired shape in the operating room.

By providing a substantial number of implants of different sizes in theoperating room and/or by cutting an implant to obtain a desiredconfiguration, it is possible for a surgeon to make a recess 610 to ashape which corresponds to a defective area on a portion of the femur126. An implant 626 having the configuration of the particular recesscan then be provided. This enables the surgeon to remove a relativelysmall defective area of the bone forming the articular surface on thefemur 126 and to minimize the size of the implant 626.

It is believed that it will be desired to provide a series of implantsof different sizes ranging from a relatively small size to a relativelylarge size. In addition, it is believed that it will be desired toprovide a plurality of guides 620. The guides 620 will have surfaces toguide movement of the milling cutter 614 or other cutting tool to form arecess 610 of a size corresponding to any one of the sizes of theimplants in the series of implants. Thus, the plurality of guides 620would be provided with each guide having guide surfaces corresponding tothe configuration of an implant of a different size.

The scaffold or base of the implant 626 may be formed of a porousbio-degradable material. The porous bio-degradable material provides amatrix for demineralized bone, collagen, bone morphogenetic protein,growth factors, and autogenous bone marrow. In addition, progenitorcells, stem cells and/or fetal cells may be disposed on the scaffold.Some non-tissue-derived components may include coralline-based HA(ProOsteon), antibiotics, calcium sulfate, calcium and phosphorus oxiderich amorphous glass, anti-inflammatories, and bovine fibrillarcollagen. The resulting material will have osteoinductive andosteoconductive qualities. Cortical cancellous bone chips which arefreeze dried may be provided in the implant 626. In addition,demineralized bone matrix may be provided in the implant 626.

The implant 626 may be secured in the recess 610 with a suitableadhesive. There are many different known adhesives which may be used.Fibrin can be used as an adhesive, either in a natural state or afterbeing compressed, to hold material together and to hold the implant 626in the recess 610.

It is contemplated that the patient's leg 70 may be in the positionillustrated in FIGS. 2, 3 and 25 during forming of the recess 610 andpositioning of the implant 626 in the recess. The upper portion 72 ofthe patient's leg 70 may be supported above the support surface 64 bythe leg support 80. The limited incision 114 (FIG. 6) may be formed inthe knee portion 76 of the patient's leg. The patella 120 may be in theoffset position of FIG. 8 during forming of the recess 610.

The drapery system 100 of FIGS. 4 and 5 may advantageously be utilizedto provide a sterile field. Although it may be desired to use a millingcutter as the cutting tool 614 (FIG. 44), other known cutting toolscould be used if desired. For example, a laser or ultrasonic cuttingtool could be used to form the recess 610.

Although it is believed that it will be preferred to have the patient'sleg 70 in the position illustrated in FIGS. 2, 3 and 25, to support thepatient's leg 70 with the leg support 80, to offset the patella 120, andto use the drapery system 100, the implant 626 may be positioned in apatient's leg 70 without using any one or any combination of thesefeatures. Thus, the implant 626 could be positioned in a patient's leg70 with the leg in the position shown in FIG. 1 with any known draperysystem. The patella may be everted (FIG. 7) rather than offset.

The foregoing description of the implant 626 has assumed that theimplant is to be positioned in the femur 126 in a leg of a patient.However, the implant 626 could be positioned in any desired bone in apatient's body. The implant 626 could be positioned at a location remotefrom an articular surface of a bone. The implant 626 may be positionedon a bone in ways other than positioning the implant in a recess similarto the recess 610.

Inlaid Implant—Tibia

The implant 626 is illustrated in FIG. 43 in association with a femur126 in a patient's body. It is contemplated that a similar implant 640(FIG. 46) may be provided in the proximal end portion 212 of the tibia214 in a leg 70 of the patient. The implant 640 is disposed in a recess642. The recess 642 may have any desired configuration. It iscontemplated that the configuration of the recess 642 would be afunction of the configuration of defective portions of the bone in theproximal end portion 212 of the tibia 214.

The recess 642 is surrounded by an articular surface 644 of naturallyoccurring bone. Thus, the articular surface 644 is not defective andextends around the recess 642. It should be understood that the extentof the articular surface 644 around the recess 642 could besubstantially greater than is illustrated in FIG. 46 relative to thesize of the implant 640. This is because the implant 640 is sized andhas a configuration which is a function of the size and configuration ofan area which was previously defective bone on the proximal end portion212 of the tibia 214. The articular surface 644 is load bearing andfunctions to transmit forces between the tibia 214 and the femur 126 inthe leg 70 of the patient.

The recess 642 is formed with the milling cutter 614 (FIG. 47). A guide620 is provided to control the depth to which the milling cutter 614removes bone from the proximal end portion 212 of the tibia 214 in themanner previously explained in conjunction with femur 126 (FIGS. 43-45).The guide 620 and milling cutter 614 are utilized to form the recess 642in a manner which is similar to that disclosed in U.S. Pat. No.5,908,424. Rather than being formed by the use of a milling cutter 614and guide 620, it is contemplated that the recess 642 in the proximalend portion 212 of the tibia 214 and/or the recess 610 in the distal endportion 124 of the femur 126 could be formed by a robot having aconstruction similar to the construction of the robot 370 of FIG. 33.

The implant 640 (FIGS. 46 and 48) may be formed of metal or a hardpolymeric material. Alternatively, the implant 626 may be of a layeredconstruction with a layer of metal backed by polymeric material. Thesurface of the implant forms a portion of the overall articular surfaceon the proximal end portion 212 of the tibia 214.

Of course, the articular surface area on the proximal end portion 212 ofthe tibia 214 cooperates with articular surface areas on the distal endportion 124 of the femur 126 (FIG. 43). It is contemplated that theimplant 626 in the femur 126 and the implant 640 in the tibia 214 (FIG.46) could be disposed in engagement with each other. Alternatively, theimplant 626 in the distal end portion 124 of the femur 126 (FIG. 43)could be engaged by a naturally occurring articular surface on theproximal end portion 212 of the tibia 214 (FIG. 46). Similarly, theimplant 640 in the proximal end portion 212 of the tibia 214 may engagea naturally occurring articular surface area on the distal end portion124 of the femur 126.

It is contemplated that it may be preferred that the implant 640 containbone growth promoting materials and/or materials which promotebiological resurfacing. These bone growth promoting materials wouldpromote growth of bone from the proximal end portion 212 of the tibia214 into the recess 642. This would result in the recess 642 beingfilled with new bone growth. The biological resurfacing materials wouldpromote the growth of naturally occurring tissues on the implant 640.

The implant 640 may include a three dimensional scaffold or frameworkstructure formed of either a biodegradable material or anon-biodegradable material. Osteoinductive and/or osteoconductivematerials may be disposed on this framework or platform. The scaffoldmay be formed of cortical bone, cartilage submucosal tissue, or othermaterials.

The matrix or scaffold for the implant 640 has interstitial spaces whichcontain material which promotes the growth of bone from the proximal endportion 212 of the tibia 214 into the matrix or scaffold. The bonegrowth materials may include bone morphogenic protein, factors thatstimulate migration of cells, anti-inflammatories and/or immunosuppressants. Collagen, fibrin, osteoinductive materials, progenitorcells, and/or tissue inductive factors may be disposed on the platform.The implant 640 may contain cortical cancellous bone chips ordemineralized bone matrix. It may be preferred to form the outer surfaceof the implant 640 of materials which promote biological resurfacing.

When the implant 640 is formed with a biodegradable three dimensionalscaffold or matrix, it is contemplated that there will be cellularmigration and growth of bone from the proximal end portion 212 of thetibia 214 into the scaffold or matrix. The scaffold or matrix will thendegrade and disappear as material of the scaffold or platformhydrolyzes. However, if the matrix or scaffold is made of anon-biodegradable material, it is contemplated that the scaffold willbecome embedded in the bone growth from the proximal end portion 212 ofthe tibia 214 into the recess 614. The scaffold, whether biodegradableor non-biodegradable, may be impregnated with mesenchymal cells.

The implant 640 on the tibia has the same construction as the implant626 on the femur. However, the implant 640 on the tibia could have aconstruction which is different than the construction of the implant 626on the femur.

It is contemplated that the patient's leg will be in the positionillustrated in FIGS. 2, 3 and 25 during forming of the recess 642 andpositioning of the implant 640 in the recess. The upper portion 72 ofthe patient's leg 70 will be supported above the support surface 64 bythe leg support 80. The limited incision 114 (FIG. 6) will be formed inthe knee portion 76 of the patient's leg. The patella 120 will be in theoffset position of FIG. 8 during forming of the recess 642. The draperysystem of FIGS. 4 and 5 may advantageously be utilized to provide asterile field. Although it may be desired to use a milling cutter as thecutting tool, other known cutting tools could be used if desired.

Layered Implant

A multi layered inlaid implant 670 for use in biological resurfacing isschematically illustrated in FIG. 49. The implant 670 is disposed in arecess 672 formed in a bone 674. The recess 672 is formed in the samemanner as is illustrated in FIGS. 44 and 47 for forming the recess 610and the recess 642. The recess 672 may be disposed in a defectiveportion of an articular surface on the distal end portion 124 of a femur126, as illustrated in FIG. 43, or may be located at a defective portionof an articular surface on the proximal end portion 212 of a tibia 214as illustrated in FIG. 46. However, it is contemplated that the implant670 may be disposed in the bone 674 at many different locations. Atleast some of these locations would be spaced from an articular surfaceon the bone. The bone may be located in many different portions of apatient's body, for example, a shoulder, spine, arm, hand, hip or foot.

The implant 670 is formed by a plurality of layers. The specific implant670 illustrated in FIG. 49 has a base layer 678 and an outer layer 680.It should be understood that more than two layers could be provided ifdesired. For example, an intermediate layer could be disposed betweenthe base layer 678 and outer layer 680 if desired. Each of the layers678 and 680 of the implant 670 could be formed with its own separateplatform or scaffold made of biodegradable materials. Alternatively, asingle biodegradable scaffold or matrix could extend between the twolayers 678 and 680.

The inner or base layer 678 is disposed in engagement with the bone 674.The inner layer 678 may be formed of bone growth promoting materialswhich promote migration of bone cells from the bone 674 to the baselayer 678. New bone growth into the base layer 678 will interconnect thebase layer and the bone 674. The base layer 678 may contain corticalcancellous bone power or chips and/or demineralized bone matrix, bonemorphogenic protein, anti-inflammatories and/or immuno suppressants maybe disposed in the base layer 678. An antibiotic, hydroxyapatiate,tricalcium phosphate and/or polymers and copolymers may also be includedin the base layer 678.

The outer layer 680 may be formed of cartilage. Embryonal cells, fetalcells, and/or stem cells may be provided in the outer layer 680. Theouter layer 680 may be formed of submucosal tissue. The outer layer 680promotes biological resurfacing of a portion of the bone 674 where theimplant 670 is disposed.

It is contemplated that the recess 672 may be formed in the bone 674 ata location where there is a defect in an articular surface on the bone.However, it is also contemplated that the recess 672 in a position in aportion of the bone 674 where there is no articular surface.

It is contemplated that the patient's leg will be in the positionillustrated in FIGS. 2, 3 and 25 during forming of the recess 672 andpositioning of the implant 670 in the recess. The upper portion 72 ofthe patient's leg 70 will be supported above the support surface 64 bythe leg support 80. The limited incision 114 (FIG. 6) will be formed inthe knee portion 76 of the patient's leg. The patella 120 will be in theoffset position of FIG. 8 during forming of the recess 672. The draperysystem of FIGS. 4 and 5 may advantageously be utilized to provide asterile field. Although it may be desired to use a milling cutter as thecutting tool, other known cutting tools could be used if desired.

Implant

An improved implant 690 is illustrated in FIG. 50. The implant 690 maybe utilized in association with either a full or partial kneereplacement. Alternatively, the implant 690 could be utilized inassociation with a repair of a glenoid joint, an elbow, an ankle, aspine or any desired joint in a patient's body. Implant 690 includes abase 692 and an articular layer 694. The base 692 has been illustratedin FIG. 50 as being connected with the proximal end portion 212 of atibia 214. The implant 690 is intended for use in association witheither a partial or full knee replacement. However, it should beunderstood that an implant having a construction corresponding to theconstruction of the implant 690 could be utilized in association withany desired joint in a patient's body.

The base 692 (FIG. 50) is connected with the tibia 214 by projection 700and a fastener 702. The projection 700 has a generally cylindricalconfiguration and extends from a main section 706 of base 692. Theprojection 700 extends at an acute angle to the main section 706 in adirection away from the fastener 702.

When the implant 690 is positioned on the proximal end portion 212 ofthe tibia 214, the implant is moved along a path which extends parallelto a longitudinal central axis of the projection 700. The path ofmovement of the implant 690 onto the proximal end portion 212 of thetibia 214 is indicated by an arrow 707 in FIG. 50. The arrow 707 isskewed at an acute angle to a longitudinal central axis of the tibia214. This results in the projection 700 being forced into the bone ofthe proximal end portion 212 of the tibia 214. Deformation of the boneoccurs adjacent to a leading end of the projection 700. There is nosignificant deformation of the adjacent to a longitudinally extendingouter side surface of the generally cylindrical projection 700.

As the implant 690 is moved into position on the proximal end portion212 of the tibia 214, a downwardly extending flange 708 connected withthe main section 706 moves into engagement with an outer side surfacearea on the tibia 214 as the main section 706 of the implant 690 movesinto engagement with flat proximal end surface 710 on the tibia 214.Once the inner side of the main section 706 has been pressed firmlyagainst the flat end surface 710 on the tibia 214 and the projection 700is moved to the position illustrated in FIG. 50, the fastener 702 isinserted through the flange 708. The fastener 702 is a screw and engagesthe proximal end portion 212 of the tibia 214 to securely connect theimplant 690 with the tibia. A longitudinal central axis of the fastener702 extends generally parallel to a longitudinal central axis of theprojection 700. Therefore, as the fastener 702 is tightened to press theflange 708 against the outer side of the tibia 214, the projection 700is cammed or forced inward to press the main section 706 against the endsurface 710 on the tibia.

It is contemplated that the base 692 of the implant 690 may be formed ofmetal. For example, the base 692 may be formed of porous tantalum. Ofcourse, the base 692 could be formed of a different material if desired.Thus, the base 692 could be formed of a polymer or copolymer if desired.The articular layer 694 is formed of a smooth polymeric material whichengages in articular surface on a femur.

It is contemplated that the patient's leg will be in the positionillustrated in FIGS. 2, 3 and 25 during positioning of the implant 690on the proximal end portion of the tibia 214. The upper portion of thepatient's leg 70 will be supported above the support surface 64 (FIG. 2)by the leg support 80. The limited incision 114 (FIG. 6) will be formedin the knee portion 76 of the patient's leg 70. The patella 120 will bein the offset position of FIG. 8 during positioning of the implant 690.The drapery system 100 (FIGS. 4 and 5) will provide a sterile field. Thetibial resection guide 218 (FIG. 21) may be used during forming of theflat end surface 710 on the tibia 214.

Expandable Devices

In accordance with another feature of the invention, one or moreexpandable devices 720 and 722 (FIG. 51) may be utilized to move,stretch, or separate body tissue. The expandable devices 720 and 722 maybe utilized at any time during a full or partial knee replacement. Thus,the expandable devices 720 and 722 may be utilized to separate bodytissue from the distal end portion 124 of a femur 214 before a femoralcomponent or implant 290 is connected with the femur and before thetibial tray 286 and tibial bearing insert 294 are connected with theproximal end portion 212 of the tibia 214.

The expandable devices 720 and 722 may be inserted into the knee portion76 of the patient's leg 70 one or more days before either a partial orfull knee replacement operation is to be undertaken. Before the surgeryis initiated, the expandable device 720 may be expanded to stretch skin342, the joint capsule, and other tissue in the anterior of the kneeportion 76. The viscoelastic body tissue is resiliently stretched by theexpandable device 720 in the general area where the limited incision 114(FIG. 6) is to be formed.

The incision 114 is subsequently made in the body tissue which has beenresiliently stretched by the expandable device 720. After the surgery onthe patient's leg 70 has been completed, for example, after a full orpartial knee replacement in accordance with FIGS. 8-29, the incision 114in the stretched tissue is closed. The body tissue which was previouslyresiliently stretched by the expandable device 720 can, after closing ofthe incision 114, return to its normal or unstretched condition. As thisoccurs, the length of any scar resulting from the incision 114decreases. By making the incision 114 in body tissue which haspreviously been resiliently stretched by the expandable device 720, theoverall effective length of the incision 114 is reduced.

The expandable devices 720 and 722 may be resilient balloons which areinflated by a gas, such as air, or resilient bladders which are expandedunder the influence of a liquid, such as saline solution. The resilientexpandable devices 720 and 722 may be formed of a biodegradable materialor a non-biodegradable material. It is contemplated that if theexpandable devices 720 and 722 are to be left in the patient's body,they may advantageously be formed of a biodegradable material. However,if it is contemplated that when the expandable devices are to be removedfrom the patient's body during or after surgery, the expandable devicesmay be formed of a non-biodegradable material.

Rather than being inserted into the knee portion 76 prior to formationof the incision 114, the expandable devices 720 and 722 (FIG. 51) may beinserted into the knee portion immediately after making the incision.The expandable devices 720 and 722 may then be expanded to separate bodytissue in the knee portion 76. The expandable devices 720 and 722 areinserted into the knee portion 76 in a collapsed condition. Theexpandable devices are expanded after being inserted into the kneeportion.

For example, the expandable device 720 may be resiliently expanded tostretch the patellar ligament 458 (FIG. 51) and move the patella 120away from the distal end portion 124 of the femur 126. Alternatively,the expandable device 720 may be positioned between the femur 126 andthe patellar tendon 456. Expansion of the expandable device 720 wouldthen result in movement of the patellar tendon 456 and patella 120 awayfrom the distal end portion 124 of the femur 126. Of course, ifexpandable devices were provided between the distal end portion 124 ofthe femur and both the patellar tendon 456 and patellar ligament 458,the patella tendon and ligament would both be moved by expansion of theexpandable devices. Positioning of the expandable device 720 between thepatellar ligament and/or tendon facilitates subsequent movement of thepatella 120 to offset position of FIG. 8. As previously noted,expandable device 720 can be used to access the inner surface of thepatella 120.

The expandable device 722 (FIG. 51) is disposed in the posterior portionof the knee portion 76 of the leg 70. Expansion of the expandable device722 in the posterior portion of the patient's knee is effective to movethe joint capsule and fibrous connective tissue away from the distal endportion 124 of the femur 126 and the proximal end portion 212 of thetibia 214. The expandable device 722 may be expanded immediately afterthe incision 114 is formed to effect releases of body tissue from thedistal end portion 124 of the femur 126 and/or the proximal end portion212 of the tibia 214.

Expansion of the expandable device 722 is effective to move arteries,nerves and veins in the posterior of the knee portion 76 away from thedistal end portion 124 of the femur 126 and proximal end portion 212 ofthe tibia 214 prior to making of the femoral and/or tibial cuts (FIGS.8-29). If desired, the expandable device 722 may be maintained in theexpanded condition during making of one or more of the femoral and/ortibial cuts. If desired, the expandable device 722 may be provided witha tough surface which would protect arteries, nerves and/or veins duringthe making of one or more of the femoral and tibial cuts.

It should be understood that the expandable device 722 may have aconfiguration which is different from the configuration illustrated inFIG. 51. For example, the expandable device 722 may extend for a greaterdistance along the posterior of the femur 126 and tibia 214 if desired.Although the implants 286, 290 and 294 have been illustrated in FIG. 51,it should be understood that the expandable devices 720 and 722 may beused before and/or after installation of the implants. The expandabledevices 720 and 722 may be positioned in the knee portion 76 of thepatient's leg 70 with the leg in the flexed condition of FIGS. 2 and 3or with the leg in the extended condition of FIG. 51.

After the femoral component 290 and tibial tray 286 and tibial bearinginsert 294 have been positioned in the knee portion 726 of the patient'sleg 70, the expandable devices 720 and 722 may be utilized to assist thesurgeon during ligament balancing. The expandable devices 720 and 722will also assist the surgeon in obtaining a full range of motion of theknee portion 76. Thus, the expandable devices 720 and 722 may beexpanded, under the influence of fluid pressure, to effect ligamentreleases or to move tissue out of an interfering relationship withrelative movement between the femur 126 and tibia 214.

The expandable devices 720 and 722 may be resiliently expanded under theinfluence of fluid pressure conducted through conduits to the expandabledevices. If the expandable devices 720 and 722 are inserted after theincision 114 is formed in the knee portion 76 of the patient's leg 70,the conduits for conducting fluid to and from the expandable devices 720and 722 may extend through the incision. However, if the expandabledevices 720 and 722 are inserted prior to making of the incision 114,the conduits for conducting fluid to and from the expandable devices mayextend through small portals or stab wounds formed in the knee portionof the patient's leg. It should be understood that the conduits forconducting fluid to and from the expandable devices 720 and 722 mayextend through small secondary incisions spaced from the main incision114 even though the expandable devices 720 and 722 are positioned in theknee portion 76 after making the main incision.

The small portals or stab wounds which form secondary incisions arespaced from the location where the main incision 114 is formed. Thus,the conduit for conducting fluid to and from the expandable device 722may extend through a portal or stab wound formed in the posteriorportion of the knee portion 76 of the patient's leg 70. Before they areexpanded, the contracted expandable devices 720 and 722, are very smalland flexible. The contracted expandable devices 720 and 722 have anappearance similar to a collapsed balloon. The contracted expandabledevices are easily moved through the small secondary incisions.

It is contemplated that the expandable devices 720 and 722 may be leftin the knee portion 76 of a patient's leg 70 after the incision 114 hasbeen closed. If this is done, the expandable devices 720 and 722 may beutilized to obtain a full range of motion of the patient's knee 76during therapy and/or recovery of the patient after the incision hasbeen closed. If the expandable devices 720 and 722 are formed of anon-biodegradable material, it may be desirable to remove the expandabledevices after the incision 114 has been closed. If the expandabledevices 720 and 722 are formed of a biodegradable material, they do nothave to be removed after the incision has been closed. It iscontemplated that the expandable devices 720 and 722 may be contractedby piercing the skin 342 and puncturing the expandable devices.

It is contemplated that it may be desired to form the expandable devices720 and 722 (and/or the conduits for inflating expandable devices 720and 722) of a biodegradable material which is absorbable by thepatient's body. If this is done, the expandable devices 720 and 722 maybe formed of polyglycolic acid, polylactic acid, or combinations ofthese materials. It is contemplated that the expandable devices 720 and722 could be formed of materials which include hyaluronic acid, catgutmaterial, gelatin, cellulose, nitrocellulose, collagen or othernaturally occurring biodegradable materials. Although it is believedthat it would be preferred to form the expandable devices 720 and 722 ofbiodegradable materials so that they can be left in the patient's bodyand hydrolyzed so as to be absorbed by the patient's body, it iscontemplated that the expandable devices 720 and 722 could be made of anon-biodegradable material if desired. The resiliently expandabledevices 720 and 722 may have any of the constructions disclosed in U.S.Pat. Nos. 5,163,949; 5,454,365 and 5,514,153. Of course, the resilientlyexpandable devices 720 and 722 could have a different construction ifdesired.

Obtaining Range of Motion

After the implants 286, 290 and 294 have been positioned on the femur126 and tibia 214 in the manner illustrated schematically in FIG. 52, itis contemplated that the range of motion of the knee portion 76 will bechecked. During the check of the range of motion of the knee portion 76,it may be found that the range is unduly limited due to interferencebetween body tissue in the posterior of the knee portion 76 and theimplants. The range of motion of the knee portion 76 may be limited bytightness of tendons, ligaments and/or other tissue in the knee portion76.

Although it is believed that the expandable devices 720 and 722 of FIG.51 may be utilized to alleviate these conditions, it may be preferred touse an expandable device 730 (FIG. 52) which is inserted between thetibial bearing insert 294 and the trochlear groove in the femur 126.Thus, once the implants 286, 290 and 294 have been positioned in theknee portion 76 of the patient's leg 70, the expandable device 730 maybe moved through the incision 114. The expandable device 730 is thenmoved between the distal end portion 124 of the femur 126 and theproximal end portion 212 of the tibia 214.

The expandable device 730 may be a balloon or bladder which is made ofresilient material. When fluid pressure in the expandable device 730 isincreased, the expandable device is expanded from a collapsed conditionto an extended condition. The resilient material of the expandabledevice 730 may or may not be stretched when the expandable device 730 isexpanded.

The expandable device 730 may be moved posteriorly of the implants 286,290 and 294 so as to engage tissue in the posterior portion of thepatient's knee. Alternatively, the expandable device 730 may bepositioned between the distal end portion 124 of the femur 126 and theproximal end portion 212 of the tibia 214. It is contemplated that thepatient's leg 70 will be in the position illustrated in FIGS. 2 and 3with the patella 120 (FIG. 52) offset when the expandable device 730 ispositioned in the knee portion 76.

When the expandable device 730 is moved to the posterior of thepatient's knee portion 76, expansion of the expandable device 730applies pressure against tissue in the posterior portion of thepatient's knee. This results in movement of body tissue away from theimplants 286, 290 and 294. Assuming that body tissue in the posterior ofthe patient's knee portion 76 is interfering with the range of relativemovement between the implants 286, 290 and 294, applying pressureagainst the body tissue in the posterior of knee portion will move thebody tissue away from the implants to enable the range of motion to beincreased.

Expansion of the expandable device 730 is effective to move and stretchbody tissue, such as the joint capsule, ligaments, tendons, skin orother tissue associated with the posterior portion of the patient'sknee. Space is established between the distal end portion 120 of thefemur 126 and body tissue. Space is also established between theproximal end portion 212 of the tibia 214 and body tissue. Since thebody tissue is moved and stretched by expansion of the expandable device730, a portion of the space tends to remain even though the viscoelasticbody tissue retracts when fluid is conducted from the expandable device730 and the size of the device decreases.

The expandable device 730 may be left in place in the posterior of thepatient's knee portion 76 after the incision 114 is closed. A conduit734 connected with the expandable device 730 would extend through theclosed incision 114 to enable fluid to be conducted to and from theexpandable device 730. Therefore, after the incision 114 has beenclosed, the expandable device 730 can be expanded to increase the rangeof movement of the knee portion 76 of the patient's leg 70. After fluidhas been conducted from the expandable device through the conduit 734,the size of the expandable device is reduced by exhausting fluid throughthe conduit. The reduced size of the expandable device enables theconduit 734 to be pulled outward, away from the knee portion 76, to pullthe expandable device 730 through a very small opening in the closedincision.

If desired, the expandable device 730 could be formed of a biodegradablematerial and left in the posterior of the knee portion 76. The conduit734 could be formed of a non-biodegradable material and pulled from theopening in the incision after the expandable device 730 has at leaststarted to degrade. Of course, the conduit 734 could also bebiodegradable.

Rather than applying force against body tissue at the posterior of theknee portion 76, the expandable device 734 may be utilized to applyforce against the distal end portion 124 of the femur 126 and againstthe proximal end portion 212 of the tibia 214. This force would tend tostretch or release ligaments or other fibrous connective tissueconnected with the femur 126 and tibia 214. This force would alsostretch the joint capsule, collateral ligaments 590 and 592 (FIG. 41),and other tissues around the distal end portion 124 of the femur 126 andthe proximal end portion 212 of the tibia 214.

When this is to be done, the expandable device 730 (FIG. 52) is moved toa position midway between posterior and anterior portions of theimplants 286, 290 and 294. The expandable device 730 is then expandedunder the influence of fluid pressure conducted through the conduit 734.As the expandable device expands, it acts as a joint jack to apply forceagainst the femur 126 and tibia 214. This force will tend to stretch thecollateral ligaments and other ligaments and tendons connected with thefemur 126 and tibia 214.

Once the expandable device 730 has been utilized to apply an upwardlydirected force (as viewed in FIG. 52) against the distal end portion 120of the femur 126 and a downwardly directed force (as viewed in FIG. 52)against the proximal end portion 212 of the tibia 214, the expandabledevice 730 is contracted by conducting a flow of fluid from theexpandable device through the conduit 734. The surgeon can then checkligament balancing and/or the range of motion of the knee portion 76. Ifthe ligament balancing check and/or range of motion check indicates thatit would be beneficial, the expandable device 730 can again be utilizedto apply force against the femur 126 and tibia 214. Fluid pressure wouldagain connected through the conduit 734 to the expandable device 730.Expansion and contraction of the expandable device 730 can be repeatedas many times as necessary to obtain the desired ligament balancingand/or range of motion of the knee portion 76.

In FIG. 52, the leg 70 of the patient is in the position indicated inFIGS. 2, 3 and 25. However, the leg 70 of the patient could be movedfrom the flexed position of FIG. 52 to the extended condition of FIG. 51with the expandable device in position between the distal end portion120 of the femur 126 and the proximal end portion 212 of the tibia 214.It should be understood that the expandable devices 720, 722 and 730 ofFIGS. 51 and 52 may be utilized with the leg 70 of the patient in eitherthe extended orientation of FIG. 51 or the flexed orientation of FIG.52. The leg 70 of the patient may be maintained stationary afterinsertion of the expandable devices 720, 722 and/or 730. Alternatively,the patient's leg 70 may be moved in any one or a combination of thedirections indicated by the arrows 256, 258, 259 and 260 in FIG. 25after insertion of the expandable devices 720, 722 and/or 730.

Although a single expandable device 730 is illustrated in FIG. 52, itshould be understood that a plurality of expandable devices 730 could beinserted into the knee portion 76 of the patient's leg. A first one ofthe expandable devices 730 may be inserted into the posterior of theknee portion 76. A second expandable devices 730 may be positionedbetween the lateral portions of the femur 126 and tibia, that is, in aposition similar to the position of the transducer 596 in FIG. 41. Athird expandable device 730 may be positioned between medial portions ofthe femur 126 and tibia 214, that is, in a position similar to theposition of the transducer 598 in FIG. 41.

It is contemplated that different pressures may be conducted to theexpandable devices in different positions in the knee portion 76. Forexample, a relatively low fluid pressure may be conducted to the firstexpandable device 730 in the posterior of the knee portion 76 to moveand/or stretch body tissue with a limited force. A relatively high fluidpressure may be conducted to the second and third expandable devices 730disposed between the femur 126 and tibia 214 to effect relative movementbetween the femur and tibia.

If desired, a higher fluid pressure could be conducted to one of theexpandable devices 730 disposed between the femur 126 and tibia 214 thanthe other expandable device. For example, a higher fluid pressure may beconducted to the second expandable device 730 disposed between lateralportions of the femur 126 and tibia 214 than to the third expandabledevice 730 disposed between the medial portions of the femur and tibia.Alternatively, a higher fluid pressure may be conducted to the thirdexpandable device 730 disposed between medial portions of the femur 126and tibia 214 than to the second expandable device 730 disposed betweenlateral portions of the femur 126 and tibia 214.

When a plurality of expandable devices 730 are used, the expandabledevices may be made of the same material or different materials. Forexample, the first expandable device 730 in the posterior of the kneeportion may be fanned of a biodegradable material. The second and thirdexpandable devices 730, located between the femur 126 and tibia 214, maybe formed of a non-biodegradable material. Alternatively, the expandabledevices 730 may all be formed of the same biodegradable material as theexpandable devices 720 and 722.

It is contemplated that the expandable devices 720, 722 and/or 730 ofFIGS. 51 and 52 may be utilized in association with many differentjoints in a patient's body. For example, the expandable devices may beutilized in association with surgery on a glenoid joint. Alternatively,the expandable devices may be used in association with surgery on apatient's spine. During spinal surgery, the expandable devices 720, 722and/or 730 may be utilized to move one vertebra relative to an adjacentvertebra during replacement of an intravertebral disc between thevertebrae. If desired, the expandable devices 720, 722 and 730 could bepositioned between articular processes on vertebrae. When the expandabledevices 720, 722 and 730 are formed of a biodegradable material, theymay be positioned relative to a patient's vertebral column duringsurgery and left in place after the surgery. This would allow at leastpartial healing after the surgery with the expandable devices beingeffective to transmit force between components of the patient'svertebral column.

The manner in which the expandable devices 720, 722 and 730 may beutilized in association with any one of many joints in the patient'sbody is similar to that disclosed in U.S. patent application Ser. No.09/526,949 filed on Mar. 16, 2000. The manner in which an expandabledevice similar to the expandable devices 720, 722 and 730 may be placedwithin a shoulder joint is similar to the disclosure in theaforementioned application Ser. No. 09/526,949 of which this applicationis a continuation-in-part. The expandable devices 720, 722 and 730 maybe utilized during carpal tunnel surgery in the manner disclosed in theaforementioned application Ser. No. 09/526,949. It is believed that itwill be particularly advantageous to make the expandable devices 720,722 and 730 of biodegradable material so that they may be left in apatient's body at the end of the surgery.

As previously mentioned, the expandable devices 720, 722 and 730 may beutilized during therapy after surgery to stretch body tissue in the kneeportion 76 of the patient's leg 70 and/or to increase the range ofmotion of the knee portion. It is contemplated that an orthosis may beutilized to stretch tissue that limits joint movement. The orthosis mayhave a construction similar to the construction disclosed in U.S. Pat.No. 5,611,764. The orthosis may be utilized to affect static progressivestretching of tissue in the knee portion 76 of the patient's leg 70. Inaddition, the orthosis may be utilized during progressive stressreduction. The orthosis may be utilized in conjunction with one or moreexpandable devices corresponding to the expandable devices 720, 722 and730 in the patient's knee portion. Alternatively, the orthosis may beutilized without providing expandable devices in the patient's kneeportion.

It is contemplated that, during restoration of the range of motion ofthe knee portion 76, a constant passive motion device may be connectedwith the patient's leg. The constant passive motion device may includeone or more load or force limiting devices similar to those disclosed inU.S. Pat. No. 5,456,268. The constant passive motion device may have aconstruction similar to that illustrated in U.S. Pat. No. 5,285,773. Ofcourse, the constant passive motion device may have a differentconstruction if desired. It is contemplated that a pulsatile stockingmay be utilized to reduce the possibility of blood clots while aconstant passive motion machine is utilized to increase the range ofmotion of the knee portion of a patient's leg.

It is contemplated that a laminar spreader may be used in associationwith the knee portion 76 during ligament balancing and/or gap balancingwith the implants 286, 290 and 294. Alternatively, a distraction devicewhich is spring loaded may be utilized on a medial, lateral or bothsides of the knee portion 56 rather than the expandable elements 720,722 and 730 to increase range of motion and/or provide a desiredligament balancing. Insol's technique may be utilized in establishing adesire range of motion of the knee portion 76 of the patient's leg 70.

Surgical Procedure

In the foregoing description of a specific surgical procedure which maybe utilized in association with a knee portion 76 of a patient's leg,the femoral and tibial cuts are made, the patella is repaired andimplants are installed in the knee portion 76 of the leg 70. However, itis contemplated that the various steps in this surgical operation may beperformed in a different order if desired.

Immediately after the limited incision 114 (FIG. 6) is made in the kneeportion 76 in the manner previously explained, repair of the patella 120may be undertaken. During repair of the patella 120, the patient's leg70 is in the position illustrated in FIGS. 2 and 3. The patella 120 iscut in situ with the guide assembly 464 (FIG. 36). After a flat surfacehas been cut along the plane 484 (FIG. 35) to form a flat surface on theinside of the patella, a layer on which the inner side 122 of the paellais disposed is removed. This decreases the thickness of the paella.

After the patellar cut has been made, in the manner previously explainedand before installation of the patellar implant, the tibial cut isundertaken. During the tibial cut, the patient's leg 70 is in theposition illustrated in FIGS. 2 and 3. The proximal end portion 212 ofthe tibia 214 is cut, in the manner illustrated schematically in FIG.21.

While the tibial cut is being made, the patella 120 is offset from itsnormal position with the flat cut surface, previously formed on theinner side of the patella, facing toward the distal end portion 124 ofthe femur 126. Since the patellar cut has already been made, the patella120 is relatively thin and provides minimal stretching of the skin 342and other tissues in the knee portion 76 when the patella is in theoffset position of FIG. 21 during the making of the tibial cut.

After the tibial cut has been made, the femoral cuts are made. Making ofthe femoral cuts after making of the tibial cut and after making of thepatellar cut maximizes the space which is available for the making ofthe femoral cuts. During the making of the femoral cuts, the patient'sleg 70 is in the position illustrated in FIGS. 2 and 3. After the tibialcut has been made, a layer is removed from the tibia and the cut surface246 (FIGS. 22 and 23) on the proximal end portion 212 of the tibia isspaced from the distal end portion 124 of the femur 126. In addition,the patellar cut has been made so that the patella 120 is relativelythin and provides minimal interference. The femoral cuts are made in themanner previously explained in conjunction with FIGS. 8-20.

After the femoral cuts have been made, the tibial tray 286 is positionedon the distal end portion 212 of the tibia 214 in the manner illustratedschematically in FIGS. 27 and 28. After the tibial tray 286 has beenpositioned on the tibia 214, the femoral implant 290 (FIG. 29) ispositioned on the distal end portion 124 of the femur 126. After thefemoral implant 290 has been positioned on the distal end portion 124 ofthe femur 126, the tibial bearing insert 294 (FIG. 29) is positioned onthe tibial tray 286 in the manner previously explained.

Once the tibial and femoral implants 286, 290 and 294 have beenpositioned, the patellar implant is mounted on the cut surface of thepatella 120. The patellar implant is positioned on the cut surface ofthe patella 120 while the patella is in the medially offset positionillustrated in FIG. 29. By applying force to the patella pulling itoutward away from the distal end portion 124 of the femur 126, apatellar implant can be moved between the patella 120 and the femoralimplant 290 (FIG. 29) and mounted on the patella 120. When the patella120 has been moved back to the normal or initial position illustrated inFIG. 6, the implant on the patella is aligned with the distal endportion 124 of the femur 126.

By making the patellar cut before making of the tibial cut and thefemoral cuts, the available space for the tibial cut and femoral cuts ismaximized. Maximization of the space for the tibial cut and femoral cutsand for the insertion of the femoral implant 290 and tibial implants 286and 294 is maximized by mounting the patellar implant after the femoraland tibial implants have been mounted.

It should be understood that the foregoing procedure is performed withthe patient's leg in the position illustrated in FIGS. 2, 3 and 25.Thus, the upper portion 72 of the patient's leg is supported above thesupport surface 64 by the leg support 80. The lower portion 68 of thepatient's leg is suspended from the upper portion 72 of the patient'sleg. The foot 74 is disposed below the support surface 64.

Femoral Cutting Guide

A femoral cutting guide 750 (FIG. 53) has cutting guide slots 752 and754 with open ends 756 and 758. The guide slot 752 has parallel guidesurfaces 762. Similarly, the guide slot 754 has parallel guide surfaces764.

The guide surfaces 762 for the guide slot 752 are skewed at an acuteangle of forty-five degrees to a major side surface 766 of the femoralcutting guide 750. Similarly, the guide surfaces 764 are skewed at anangle of forty-five degrees to the major side surface 756 of the femoralcutting guide 750. The guide surfaces 762 extend perpendicular to theguide surfaces 764. The guide surface 762 guide a saw blade during themaking of an anterior chamfer resection on the distal end portion 124 ofthe femur 126. Similarly, the guide surfaces 764 guide a saw bladeduring the making of a posterior chamfer cut on the distal end portion124 of the femur 126.

The femoral cutting guide 750 has an anterior guide surface 770 whichguides movement of a saw blade during the making of an anteriorresection on the distal end portion 124 of the femur 126. Anterior guidesurface 770 extends across the femoral cutting guide 750 between thelateral end portion 774 and a medial end portion 776 of the femoralcutting guide 750. The anterior guide surface 750 extends perpendicularto the major side surface 766 of the femoral cutting guide 750.

A posterior guide surface 780 guides movement of a saw blade during themaking of a posterior resection on the distal end portion 124 of thefemur 126. The posterior guide surface 780 extends between the lateralend portion 774 and the medial end portion 776 of the femoral cuttingguide 770. The posterior guide surface 780 extends perpendicular to themajor side surface 766 and extends parallel to the anterior guidesurface 770. The anterior guide surface 770 and the posterior guidesurface 780 extend transverse to the guide surfaces 762 and 764 of theguide slots 752 and 754.

The femoral cutting guide 750 is disposed on the distal end of the femur126. The femoral cutting guide 750 is connected with the distal end ofthe femur 126 by a pair of pins 784 and 786. The pins 784 and 786 havelongitudinal central axes which extend perpendicular to the major sidesurface 766 of the femoral cutting guide 750 and extend generallyparallel to a longitudinal central axis of the femur 126.

When the femoral cuts are to be made on the distal end portion 124 ofthe femur 126, the femoral cutting guide 750 is connected to the distalend of the femur. Initial portions of the various femoral cuts are thenmade by moving the saw blade along the guide surfaces 762, 764, 770 and780 on the femoral cutting guide 750. Since the femoral cutting guide750 extends only part way across the distal end portion 124 of the femur126, the femoral cutting guide is disconnected from the femur and thefemoral cuts are completed.

After the femoral cutting guide 750 has been disconnected from the femur126, cut surfaces during formation of the initial portion of theanterior femoral cut are utilized to guide the saw blade duringcompletion of the anterior femoral cut. Similarly, cut surfaces formedduring the initial portion of the posterior femoral cut are utilized toguide the saw blade during completion of the posterior femoral cut. Cutsurfaces formed during the making of anterior chamfer cut are utilizedto guide the saw blade during completion of the anterior chamfer cut.Similarly, cut surfaces formed during making of the initial portion ofthe posterior chamfer cut are utilized to guide the saw blade duringcompletion of the posterior chamfer cut.

The cutting tool which is used to form the femoral cuts, tibial cuts,and patellar cut may have any desired construction. Although a saw 172and blade 170 have been disclosed herein as making the various cuts,many known types of cutting tools may be used if desired. For example,laser cutters, milling cutters, and/or ultrasonic cutters may beutilized. When one or more features of the present invention areutilized to perform knee joint revisions, an ultrasonic cutter mayadvantageously be utilized to cut cement previously used in associationwith an implant.

Side Cutting Guide

Using the femoral cutting guide 210 of FIG. 19 or the femoral cuttingguide 750 of FIG. 53, the femoral cuts are made by moving a saw bladefrom a distal end of the femur 126 toward a proximal end of the femur.However, it is contemplated that the femoral cuts could be made bymoving a saw blade between opposite sides of the femur in a directionextending generally perpendicular to a longitudinal central axis of thefemur. Thus, the saw blade is moved along a path which extends betweenlateral and medial surfaces on the distal end portion 124 of the femur126.

A femoral cutting guide 800 is illustrated in FIG. 54 as being mountedon a lateral surface 802 of the femur 126. However, the femoral cuttingguide 800 could be mounted on the medial surface of the femur 126 ifdesired. When the cutting guide 800 is mounted on the lateral surface802 of the femur 126, the incision 114 (FIG. 6) is laterally offset.Similarly, when the cutting guide 800 is mounted on a medial surface ofthe femur 126, the incision 114 is medially offset.

The femoral cutting guide 800 has a distal guide surface 806. The distalguide surface 806 is disposed in a plane which extends perpendicular toa longitudinal central axis of the femur 126 and extends through thelateral and medial condyles. The distal guide surface 806 extendsperpendicular to a major side surface 808 of the femoral cutting guide800.

An anterior chamfer guide surface 812 extends between opposite majorsides of the femoral cutting guide 800. The anterior chamfer guidesurface 812 is disposed in a plane which extends at an acute angle offorty-five degrees to a plane containing the distal guide surface 806.The anterior chamfer guide surface 812 extends perpendicular to themajor side surface 808 of the femoral cutting guide 800. Similarly, aposterior chamfer guide surface 816 extends between opposite major sidesof the femoral cutting guide 800. The posterior chamfer guide surface816 is disposed in a plane which extends at an acute angle of forty-fivedegrees to a plane containing the distal guide surface 806. The planecontaining the posterior chamfer guide surface 816 extends perpendicularto the plane containing the anterior chamfer guide surface 812.

An anterior guide surface 820 is disposed on the femoral cutting guide800. The anterior guide surface 820 extends between opposite major sidesof the femoral cutting guide 800. The anterior guide surface 820 isdisposed in a plane which extends perpendicular to a plane containingthe distal guide surface 806. The plane containing the anterior guidesurface 820 extends generally parallel to a longitudinal central axis ofthe femur 126.

Similarly, the femoral cutting guide 800 includes a posterior guidesurface 824. The posterior guide surface 824 extends between oppositemajor sides of the femoral cutting guide 800. The posterior guidesurface 824 is disposed in a plane which extends parallel to a planecontaining the anterior guide surface 820 and perpendicular to a planecontaining the distal guide surface 806.

The femoral guide 800 is formed of one piece of metal and has parallelopposite major side surfaces 808. The femoral cutting guide 800 isconnected with the lateral side 802 of the distal end portion 124 of thefemur 126 by a pair of pins 830 and 832. The lateral side 802 of thefemur may be cut to form a flat surface which is abuttingly engaged by amajor side surface of the femoral cutting guide 800.

When the femoral cuts are to be made, the lateral side of the femur iscut to form a flat side surface on which the femoral cutting guide 800is mounted by the pins 830 and 832. A saw blade or other cutting tool isthen moved from the lateral side to the medial side of the distal endportion 124 of the femur 126 while the saw blade or other cutting toolis guided by the distal guide surface 806 on the femoral cutting guide800. The distal guide surface 806 has an extent which is less than theextent of the distal end cut to be formed on the distal end portion 124of the femur 126. Therefore, after an initial portion of the distal endcut has been made utilizing the guide surface 806 to guide movement of asaw blade or other cutting tool, the cut surfaces are utilized to guidemovement of the cutting tool during completion of the distal end cut.

Once the distal end cut has been completed, the saw blade or othercutting tool is moved from the lateral side of the femur 126 to themedial side of the femur along the anterior chamfer guide surface 812.The cutting tool is then moved from the lateral side of the femur 126 tothe medial side of the femur along the posterior chamfer guide surface816. Since the anterior chamfer guide surface 812 and posterior chamferguide surface 816 have lengths which are less than the length of theanterior chamfer cut and posterior chamfer cut, only the initialportions of the chamfer cuts are made utilizing the guide surfaces 812and 816 on the femoral cutting guide 800. The cuts are completed byguiding movement of the saw blade or other cutting tool with thepreviously cut surfaces.

The anterior guide surface 820 is then utilized to guide movement of thesaw blade during an initial portion of an anterior cut. During making ofthe anterior cut, the saw blade or other cutting tool is moved from thelateral side to the medial side of the distal end portion 124 of thefemur 126. Since the anterior guide surface 820 is smaller than theanterior cut, surfaces formed during making of an initial portion of theanterior cut are utilized to guide the saw blade or other cutting toolduring a final portion of the anterior cut.

Similarly, the posterior guide surface 824 on the femoral cutting guide800 is utilized to guide the saw blade or other cutting tool duringmaking of a posterior cut. During the making of an initial portion ofthe posterior cut, the saw blade is moved along the posterior guidesurface 824 from the lateral side 802 of the distal end portion 124 ofthe femur 126 to the medial side. The posterior guide surface 824 isshorter than the posterior cut. Therefore, cut surfaces formed during aninitial portion of the posterior cut are utilized to guide the saw bladeduring completion of the posterior cut.

The femoral cutting guide 800 remains connected with the femur 126during the initial portion of each of the femoral cuts and duringcompletion of the femoral cuts. The femoral cutting guide 800 is not ofthe capture type. Therefore, a saw blade is free to move past the guidesurfaces 806, 812, 816, 820 and 824 during completion of the femoralcuts. If the guide surfaces 806, 812, 816, 820 and 824 were formed byslots, the femoral cutting guide 800 would have to be disconnected fromthe femur before the femoral cuts could be completed.

The femoral cutting guide 800 has been illustrated in FIG. 54 as beingmounted on the lateral side 802 of the femur 126. However, it iscontemplated that the femoral cutting guide could be mounted on themedial side of the femur if desired. The distal cuts, chamfer cuts,anterior cuts and posterior cuts were set forth as being performed inthat order. However, there is no critical order as to the sequence ofthe cuts. It is contemplated that the cuts may be formed in any desiredsequence.

During use of the femoral cutting guide 800, the patient's leg 70 can bein the orientation illustrated in FIGS. 2, 3 and 25. The drapery system100 can be utilized to maintain a sterile field during the operation onthe patient's leg.

Optical Systems

Rather than using the guide members illustrated in FIGS. 9-21, it iscontemplated that an optically created guide could be utilized. Theoptically created guide may be a three dimensional image created byprojecting a hologram onto an end portion of a bone which is to be cut.For example, a hologram may be used in projecting a three dimensionalimage of any one of the guides 138 (FIG. 11), 186 (FIG. 17), 210 (FIG.20), and 218 (FIG. 21) onto a femur 126 or tibia 214 in a patient'sbody. Alternatively, one or more beams of coherent or non-coherent lightmay be projected onto the bone which is to be cut to provide a twodimensional cutting guide.

Utilizing pre-operative templating based on images of one or more bonesin a patient's body, for example, a distal end portion 124 (FIG. 55) ofa femur 126, a hologram may be developed. The hologram is utilized witha projector 858 to create a three dimensional image 850. The illustratedthree dimensional image is of a pattern of cuts to be made on the distalend portion of the femur 126. In FIG. 55, the three dimensional image850 is visible to the surgeon 106 and is utilized to replace the femoralcutting guide 800 of FIG. 54. Rather than replacing the femoral cuttingguide 800 with a pattern of cuts as shown in FIG. 55, the threedimensional image 850 may be an image of the femoral cutting guide 800.

Although a hologram may be used to produce the three dimensional image850 which is visible to the surgeon 106, the image may be created inother ways if desired. When the visible image 850 is to be projectedonto a flat surface cut on the distal end portion 124 of the femur 126,a two dimensional image may be utilized if desired. The two dimensionalimage 850 may be accurately projected on to the flat surface on the endportion 124 of the femur 126 utilizing either coherent or non-coherentlight and known image projection techniques.

The three dimensional image 850 has visible light beams 852 and 854which define opposite ends of a sight line for guidance of a saw 172 orother cutting tool. If desired, light may be projected with a plane ofcolored light which extends between the light beams 852 and 854. Thecolored light plane extending between the light beams 852 and 854 isvisible and provides a guide for alignment of a blade 170 in a desiredspatial orientation relative to the side surface 802 on the femur 126.

The surgeon 106 moves the saw blade 170 along the colored plane of lightextending between the light beams 852 and 854. The colored plane oflight extending between the light beams 852 and 854 indicates to thesurgeon the desired spatial orientation of the saw blade 170 during themaking of a cut. A sensor connected with the saw 172 enables a computerconnected with a source 858 of the image 850 to have the plane of lightextend along each of the desired saw cuts during the making of the sawcut. Thus, during the making of the femoral cut which extends betweenthe light beams 852 and 854, a plane of colored light extends betweenthe light beams. This enables the surgeon to determine when the sawblade is properly aligned with the side surface 802 of the femur 126.When a different cut is to be made, for example, a cut between the lightbeam 852 and a light beam 862, a plane of colored light extends betweenthe light beams 852 and 862. The plane of light is visible and indicatesto the surgeon the desired spatial orientation of the blade 170 of thesaw 172 relative to the femur 126.

In addition, locating laser light beams 866 and 868 are projected fromlaser light sources 872 and 874 mounted on the saw 172. The locatinglaser light beams 866 and 868 are visible to the surgeon 106 and are ofa different color than the plane of light extending between the lightbeams 852 and 854 of the image 850. Therefore, a surgeon can visuallydetermine when the locating laser light beams 866 and 868 are alignedwith the plane of light extending between the light beams 852 and 854 ofthe image 850.

When the locating laser light beams 866 and 868 are disposed in theplane of light extending between the light beams 852 and 854, the sawblade 170 is accurately aligned with the portion of the femoral cut tobe made between the light beams 852 and 854 of the image 850. If thelocating laser light beams 866 and 868 are not disposed in the plane oflight extending the light beams 852 and 854, the saw blade 170 is not inalignment with the desired location for the femoral cut.

In addition to the visual indication provided by alignment of thelocating laser light beams 866 and 868 with the plane of light betweenthe light beams 852 and 854, audible and/or visual signals may beprovided to the surgeon indicating whether or not the locating laserlight beams 866 and 868 are in alignment with the plane of colored lightextending between the light beams 852 and 854. For example, a greenlight may be illuminated when the locating laser light beams 866 and 868are in the same plane as the light beams 852 and 854 of the image 850. Ared light may be illuminated when either or both of the locating laserlight beams 866 and 868 are not located in the plane of colored lightextending between the light beam 852 and the light beam 854. Inaddition, a warning sound, that is, an alarm, may be sounded when eitherone of the locating laser light beams 866 or 868 is offset from theplane of colored light extending between the light beams 852 and 854.

Once the femoral cut extending between the light beams 852 and 854 hasbeen completed, the saw 172 and saw blade 170 are moved into alignmentwith a plane of colored light extending between the light beam 852 and862. A second femoral cut is then made in the same manner as previouslydescribed in conjunction with the light beams 852 and 854. This processis repeated until the desired number of femoral cuts have been made.

In the embodiment illustrated in FIG. 55, the image 850 is projectedonto a side surface 802 of the femur 26. If desired, a three dimensionalimage may be projected onto all sides of the distal end portion 124 ofthe femur 126. If this is done, the image may advantageously be a threedimensional image formed by lines which define the cuts to be made. Asthe saw blade 170 moves along lines of the three dimensional image, thesaw blade 170 is moved to orientations corresponding to the orientationsof the saw blade when making the femoral cuts illustrated in FIGS.12-23. However, rather than using the cutting guides illustrated inFIGS. 12-23, the three dimensional image, corresponding to the image 850of FIG. 55, is projected onto the entire distal end portion 124 of thefemur 126. Locating laser light beams would be projected from the saw172 to indicate to a surgeon when a saw was in the desired orientationrelative to light planes forming portions of the image projected ontothe distal end 874. This enables the saw blade 170 to be locatedrelative to the distal end 874 of the femur 126 in the same manner aspreviously explained in conjunction with the side surface 802 of thefemur.

As was previously mentioned, the three dimensional image 850 may be animage of anyone of the guides 138, 186, 210, 500, 750 or 800. The sawblade 170 would be moved along the image of a guide surface on the threedimensional image of the guide. The locating laser light beams 866 and868 would indicate to the surgeon the orientation of the saw blade 170relative to the three dimensional image of a guide surface on the threedimensional image of any one of the guides 138, 186, 210, 218, 500, 750or 800. This would eliminate the heavy metal guides which havepreviously been used. When the size of any one of the three dimensionalimages of one of the guides 138, 186, 210, 218, 500, 750 or 800 is to bechanged, it is merely necessary to have a computer controlling theprojection of the three dimensional image to change a hologram beingused to project the image or to effect a change in optics through whichthe image is projected.

Once the femoral cuts have been completed, an optical measuring device,such as an interferometer, may scan the cuts to determine if they havethe desired configuration. Scanning the cuts with an optical measuringdevice may be used to eliminate the necessity of performing trials withprovisional components. Eliminating the necessity of utilizingprovisional components substantially reduces the amount of equipmentrequired during a partial or total knee replacement.

The cut surfaces on the distal end portion 124 of the femur 126 and theproximal end portion 212 of the tibia 214 are illustrated in FIGS. 22and 23. Rather than performing trials with provisional implants, the cutsurfaces on the femur 126 and tibia 214 are measured using known opticalmeasuring devices. A computer, connected with the optical measuringdevice, is utilized to compare the measurement of the cut surfaces onthe femur 216 and the tibia 214 with desired measurements for thespecific implants 286, 290 and 294 to be mounted on the femur and tibia.The computer also compares optically determined orientations of the cutsurfaces on the femur 126 and tibia 214 relative to desired orientationsof the cut surfaces.

The optical measuring device may have any one of many knownconstructions. For example, the optical measuring device may have theconstruction illustrated in U.S. Pat. No. 6,185,315 or 6,195,168 ifdesired. If an optical measuring device or other measuring deviceindicates that the cut surfaces are incorrect, a computer connected withthe source 858 (FIG. 55) of the image 850 will change the hologram tocorrespond to a next smaller size of implant. When a surgeon determinesthat the femur 126 should be cut for the next smaller size implant, thesurgeon manually enters data into the computer. In response to thisdata, the computer causes the projector 858 of the image 850 to projectan image corresponding to a next smaller size image. The saw 172 is thenutilized to cut the femur along the lines indicated by the next smallersize image. This will allow the next smaller size implant to be mountedon the femur.

It is contemplated that the projector 858 could have any desiredconstruction. For example, the projector 858 could have a constructionwhich is generally similar to the construction of apparatus disclosed inU.S. Pat. No. 6,211,976. It is contemplated that the laser light sources872 and 874 could have a construction similar to the construction ofdevices disclosed in U.S. Pat. No. 5,425,355. The laser light sources872 and 874 may have a construction which is similar to the constructionof devices which are commercially available from Laserscope, Inc. of SanJose, Calif.

It is contemplated that the patient's leg 70 will be in the positionillustrated in FIGS. 2 and 3 when either the two dimensional or thethree dimensional image is projected onto the end portion 124 of thefemur 126. The relatively small incision 114 may be resiliently expandedand/or moved relative to the distal end portion 124 of the femur 126 toallow the image 850 to be sequentially projected onto various areas onthe distal end portion 124 of the femur 126. A three dimensional imagemay be generated by any one of several known methods, including themethod disclosed in U.S. Pat. No. 5,379,133.

It is contemplated that the three dimensional image 850 may be used withprocedures other than cutting of one or more bones in a patient's leg70. For example, a three dimensional image of cuts to be made on avertebra in a patient's back may be projected onto the vertebra. Thethree dimensional image may be used in surgery involving soft tissue ina patient's body. For example, the three dimensional image may beprojected to a location in a patient's body where a vascular anastomosisor an intestinal anastomosis is to be undertaken. The three dimensionalimage may correspond to a pattern of stitches to be made betweenportions of soft body tissue. By projecting the three dimensional imageinto a patient's body at any desired location where surgery of any typeis to be undertaken, a guide is provided in the patient's body to assistthe surgeon.

The locating laser light beams 852 and 854 may be used with surgicalinstruments other than the saw 172. For example, the locating laserlight beams 852 and/or 854 could be utilized to indicate the position ofa bovie, or a needle, or forceps relative to body tissue. The locatinglaser light beams may have an intensity which is sufficient to shinethrough body tissue and enable a surgeon on one side of body tissue tovisually determine the position of a surgical instrument on the oppositeside of the body tissue.

Unicompartmental Knee Replacement

The drawings associated with the foregoing description have illustrateda full knee replacement rather than a partial knee replacement. However,it is contemplated that the previously described features of the presentinvention may be utilized with either a partial knee replacement or afull knee replacement. A femur 126 is illustrated schematically in FIG.56 and has a distal end portion 124 with a pair of condyles 890 and 892.When a partial knee replacement is to be made, only one of the twocondyles, that is the condyle 892, is cut. A saw 172 having a blade 170is used to cut the condyle 892 along a line indicated at 896 in FIG. 56.

The saw 172 is provided with laser light sources 902 and 904. The laserlight sources 902 and 904 project visible locating laser light beams 906and 908 which extend along opposite longitudinal edges of the saw blade170. The locating laser light beams 906 and 908 impinge against thecondyle 892. The locating light beams are of colored coherent lightwhich is visible to a surgeon to indicate the orientation of the sawblade 170 relative to the condyle 892.

It is contemplated that the saw 172 and blade 170 may be utilized inassociation with a guide member which is connected with the femur 126.Alternatively, a two or three dimensional image, corresponding to theimage 850 of FIG. 55, may be projected onto the distal end portion ofthe femur 126. Another alternative would be to make a line 896 on thecondyle 892 with a marking instrument.

Rather than using a saw blade 170 to make the cut in the condyle 892, itshould be understood that a different type of cutting tool could beutilized if desired. For example, a milling cutter could be used to cutalong a line 896 in FIG. 56. If a full knee replacement, rather than apartial knee replacement, is desired, both condyles 890 and 892 may becut with the saw 172 and blade 170 using the laser light sources 902 and904 to indicate the position of the saw blade relative to the distal endportion 124 of the femur 126. Once the femoral cuts have been made, anoptical measuring device may be utilized to determine whether or not thecuts are of the proper size.

Multiple Incisions

A single incision 114 is illustrated in FIGS. 6-8 to provide access tothe knee portion 76 of the patient's leg 70. As has been previouslyexplained herein, the length of the incision 114 is minimized. However,it is contemplated that the length of the incision 114 could be furtherreduced by providing one or more very small incisions 920 (FIG. 57) inthe knee portion 76 of a patient's leg 70 in association with theincision 114. The incision 920 is a small stab wound which forms aportal through the skin 342. The blade 170 of the saw 172 or othercutting tool may be moved through the small incision 920 to make one ormore femoral cuts.

After the femoral cuts have been made through the small incision 920 andthe larger or main incision 114, femoral and/or tibial implants aremoved through the main incision. By providing the small incision 920 inassociation with the larger main incision 114, the overall length of themain incision may be minimized.

During making of the incisions 114 and 970, the patient's leg 70 is inthe position illustrated in FIGS. 2 and 3. During making of the tibialand femoral cuts and insertion of the implants, the patient's leg 70 isalso in the position illustrated in FIGS. 2 and 3. If desired, one ormore expandable devices, corresponding to the expandable devices ofFIGS. 51 and 52, may be inserted through one or more small incisions 920and/or the main incision 114.

In the embodiment of the invention illustrated in FIG. 57, laser lightsources 902 and 904 are connected with the saw 172 in the mannerillustrated schematically in FIG. 56. The laser light sources providevisible locating laser light beams, corresponding to the locating laserlight beams 906 and 908 of FIG. 56.

By using more than one incision, that is, the main incision 114 and oneor more small incisions 920, cutting tools can approach and move alongthe distal end portion 124 of the femur 126 from different directions.Thus, the saw blade 170 moves from the right to the left as viewed inFIG. 57, that is, in a lateral direction, during making of a femoralcut. A cutting tool which moves through the incision 114 may move in asuperior direction along the femur 126, that is, from the distal endportion 124 of the femur 126 toward a proximal end portion of the femur.The cutting tools may be used to make cuts required for either a partialor full knee replacement.

Although it is preferred to make the incisions 114 and 920 and to cutthe femur 126 with the leg 70 of the patient in the position illustratedin FIGS. 2 and 3, it should be understood that the use of a plurality ofincisions during the surgery with the leg in other positions may bedesired. Although the foregoing description has been in conjunction withsurgery on a knee portion of a leg 70 of a patient, it is contemplatedthat the surgery could be performed on a different portion of thepatient if desired.

Patellar Tracking

A pair of transducers 596 and 598 are illustrated in FIGS. 41 and 42 tocompare tension and collateral ligaments 590 and 592. The manner inwhich the transducers 596 and 598 are positioned between the femur 126and tibia 214 is illustrated schematically in FIG. 58.

In accordance with another feature of the invention, a pair of patellartransducers 930 and 932 are disposed on an inner side of the patella120. The patellar transducers 930 and 932 are connected with a display,corresponding to the computer display areas 601 and 602 of FIG. 41. Thepatellar transducers 930 and 932 are disposed between the distal endportion 124 of the femur 126 and the patella 120.

The patellar transducers 930 and 932 have outputs which correspond toforce transmitted between the patella 120 and the femur 126. Thus, theoutput from the transducer 930 corresponds to the force transmittedbetween the lateral side of the patella 120 and a lateral side of atrochlear groove in the femur 126. Similarly, the output from thetransducer 932 corresponds to the force transmitted between a medialside of the patella 120 and a medial side of the trochlear groove in thefemur 126. By comparing the output from the patellar transducers 930 and932 during relative movement between the femur 126 and tibia 214,variations in the force transmitted between the lateral and medialportions of the patella 120 can be compared. This enables a surgeon todetermine when the patella is tracking properly relative to the femur126.

The patellar transducers 930 and 932 are resiliently expandablecontainers which hold fluid. As the force transmitted between thepatella 120 and the femur 126 increases, the pressure of the fluid inthe patellar transducers 930 and 932 increases. It is contemplated thatthe containers 930 and 932 may hold either a gas or a liquid. Pressuresignals corresponding to the pressure in the patellar transducers 930and 932 are conducted through conductors 934 and 936 to a display,corresponding to the computer displays 601 and 602 of FIG. 41. Thepatellar transducers 930 and 932 may have any desired construction whichenables them to measure the force transmitted between the patella 120and the femur 126. Thus, the transducers 930 and 932 could be of thepiezoelectric type or of a strain-gauge type.

During checking of patellar tracking with the transducers 930 and 932,the upper portion 72 of the leg 70 of the patient is supported above thesupport surface 64 by the leg holder 80 (FIG. 2). The leg 70 is movedbetween the flexed condition of FIGS. 2 and 3 and the extended conditionof FIG. 4. During movement of the leg 70 between the flexed and extendedconditions, there is relative movement between the end portion 124 ofthe femur 126 and the patella 120 (FIG. 58). During relative movementbetween the femur 126 and patella 120, the output from the patellartransducers 930 and 932 indicates the manner in which force transmittedbetween the patella and femur varies. This enables a surgeon to detectany defects in tracking of the patella 120 relative to the femur 126.

The patellar transducers 930 and 932 are mounted on the patella 120after the patellar implant has been mounted on the patella. This enablesthe patellar transducers 930 and 932 to be utilized to detect anyirregularities in the manner in which the patellar implant cooperateswith the femoral implant 290 (FIG. 29). However, it is contemplated thatthe patellar transducers may be mounted on the patella 120 before thepatellar implant is mounted on the patella. When this is to be done, thetransducers 930 and 932 may be mounted in a body having a size andconfiguration corresponding to the intended size and configuration ofthe patellar implant.

In the embodiment of FIG. 58, the patellar transducers 930 and 932extend across the patella 120 between lateral and medial edges of thepatella. However, it is contemplated that the transducers 930 and 932may extend only part way across the patella. If desired, more than thetwo illustrated patellar transducers 930 and 932 may be provided on thepatella 120.

The transducers 596 and 598 can be utilized in combination with thepatellar transducers 930 and 932 (FIG. 58). This enables the surgeon todetermine the manner in which tension varies in the collateral ligaments590 and 592 (FIGS. 41 and 42) with variations in force transmittedbetween the patella 120 (FIG. 58) and the femur 126. However, thepatellar transducers 930 and 932 may be utilized without the transducers596 and 598.

When it is determined that the patella 120 is not tracking properly,corrective action may be taken by increasing the fluid pressure ineither or both of the patellar transducers 930 and 932. If thetransducers 596 and 598 are utilized, the corrective action may includeincreasing the fluid pressure in either or both of the transducers 596and 598. The transducers 596 and 598 and the patella transducers 930 and932 are formed of resilient material which can be expanded under theinfluence of fluid pressure.

Although the patellar transducers 930 and 932 are utilized to measureforce transmitted between lateral and medial portions of the patella 120and the femur 126, the patellar transducers can be utilized to stretchor move body tissue in the same manner as the expandable devices 720,722 and 730 (FIGS. 51 and 52). By increasing the fluid pressureconducted to the patellar transducer 930 (FIG. 58), the patellartransducer expands to stretch fibrous connective body tissue connectedwith the lateral side of the patella 120. Similarly, increasing thefluid pressure conducted to the patellar transducer 932 expands thepatellar transducer 932 to stretch fibrous connective body tissueconnected with the medial side of the patella 120. Increasing the fluidpressure conducted to both patellar transducers 930 and 932 is effectiveto expand both transducers and stretch fibrous connective body tissuewith both sides of the patella 120.

The patellar transducers 930 and 932 may be formed of either abiodegradable material or a non-biodegradable material. When thepatellar transducers 930 and 932 are to be left in the knee portion 76,the patellar transducers may be formed of a biodegradable material whichis eventually absorbed by the patient's body. When the patellartransducers 930 and 932 are to be removed from the knee portion 76, thepatella transducers may be formed of a non-biodegradable material. Ifthe patellar transducers 930 and 932 are formed of a biodegradablematerial and are left in the knee portion 76 after closing of theincision 114, the patellar transducers may be expanded during therapy tostretch body tissue connected with the patella 120.

Movable Implant

The implant 690 of FIG. 50 is fixedly secured to the proximal endportion 212 of a tibia 214 by the projection 700 and fastener 702. Inthe embodiment of the invention illustrated in FIG. 59, a moveableimplant 950 is provided between the distal end portion 124 of a femur126 and a proximal end portion 212 of a tibia 214. In accordance with afeature of this embodiment of the invention, the implant 950 is freelymoveable relative to both the femur 126 and the tibia 214.

The moveable implant 950 has a smooth upper (as viewed in FIG. 59)surface 952 which is engaged by a medial portion of the distal endportion 124 of the femur. Similarly, the moveable implant 950 has asmooth lower (as viewed in FIG. 59) surface 954 which is engaged by amedial portion of the proximal end portion 212 of the tibia 214. Thissmooth upper and lower end surfaces 952 and 954 compensate for defectsin the existing surfaces on the distal end portion 124 of the femur 126and the proximal end portion 212 of the tibia 214. By providing themoveable implant 950 between the distal end portion 124 of the femur 126and the proximal end portion 212 of the tibia 214, pain which resultsfrom engagement of a surface 958 on the distal end portion 124 of thefemur 126 with a surface 960 on the proximal end portion 212 of thetibia 214 is eliminated or at least substantially reduced.

During bending of the knee portion 76 of the patient's leg 70, theimplant 950 may move relative to both the femur 126 and the tibia 214.The implant 950 can move in either a lateral or medial directionrelative to the femur 126 and tibia 214. In addition, the implant 950can move in either a posterior or anterior direction relative to thefemur 126 and tibia 214.

By having a three hundred and sixty degree (360.degree.) range ofmovement relative to both the femur 126 and tibia 214, the moveableimplant 950 accommodates relative movement between the femur and tibiawith minimal pain. This is because relative movement will occur betweenthe implant 950, femur 126 and tibia 214 at locations where frictionalforces due to irregularities on the surfaces of the femur 126 and tibia214 are minimal. In addition, the implant 950 can shift relative to thefemur 126 and tibia 214 during bending of the knee portion 76 toaccommodate irregularities in the existing surfaces 958 and 960 on thedistal end portion 124 of the femur and the proximal end portion 212 ofthe tibia.

The range of movement of the implant 950 relative to the distal endportion 124 of the femur 126 and the proximal end portion 212 of thetibia 214 is limited by engagement of the moveable implant 950 with softtissue in the knee portion 76 of the patient's leg 70. Therefore, eventhough the implant 950 can move relative to the distal end portion 124of the femur 126 and the proximal end portion 212 of the tibia 214, theimplant is held against excessive movement relative to the femur andtibia by soft tissues associated with the femur and tibia.

For example, engagement of the implant 950 with cartilage or other softtissue which is located at the peripheral aspect of the knee jointbetween the femur 126 and tibia 214 retains the implant 950 within adesired range of movement. The cartilage may be articular cartilageand/or fibrocartilage. The cartilage is engaged by peripheral surfaceson the moveable implant 952 and retains the implant in a desiredposition relative to the femur 126 and tibia 214. In addition, fibrousconnective tissue extending between the femur 126 and tibia 214 limitsmovement of the implant 950 relative to the femur and tibia.

The joint capsule in the knee portion 76 of the patient's leg may beengaged by the periphery of the implant 950 to retain the implant in adesired position. By using cartilaginous, ligamentous, or other tissuesto limit the range of movement of the moveable implant 950, the implantcan freely shift relative to the femur 126 and tibia 214 through alimited range of movement during bending of the knee portion 76 of thepatient's leg 70. If desired, growth of the tissues used to limit therange of movement of the implant may be promoted.

The moveable implant 950 is sized so as to fit the surfaces 958 and 960on the distal end portion 124 and proximal end portion 212 of the femur126 and tibia 214 (FIG. 59). The sizing is accomplished by imaging theknee portion 76 of the patient's leg. The moveable implant 950 may beone of a series of implants of different sizes. After the patient's kneeportion 76 has been imaged, a moveable implant is selected from theseries of moveable implants of different sizes. The size of the selectedmoveable implant closely approximates the size of the space between thesurfaces 958 and 960 on the distal end portion 124 and proximal endportion 212 of the femur 126 and tibia 214.

Thus, for a relatively large individual, a moveable implant 950 having arelatively large size is selected from the series of moveable implants.Similarly, for an individual having a relatively small size, a moveableimplant 950 having a relatively small size is selected from the seriesof moveable implants. The selected implant has a size which correspondsto the general size of the space between the surfaces 958 and 960.

As a result of imaging of the knee portion 76 of the patient's leg 70,the actual configurations of the existing surfaces 958 and 960 on thefemur 126 and tibia 214 can be accommodated by shaping the upper surface952 of the moveable implant 958 to have a configuration corresponding tothe surface 958 on the femur 126. Similarly, the lower surface 954 onthe moveable implant 950 can be shaped to have a configurationcorresponding to the configuration of the surface 960 on the tibia 214.Of course, the configuration of the periphery of the moveable implantcan be changed to correspond to the configuration of the periphery ofthe space between the surfaces 958 and 960 into which the moveableimplant 950 is to be placed.

It is contemplated that the imaging of the knee portion 76 of thepatient's leg 70 may be done preoperatively, on an out-patient basis.The moveable implant 950 may then be selected from the series ofavailable moveable implants and shaped to have a configuration whichcorresponds to the configuration of the space between the surfaces 958and 960. The implant 950, which has been shaped to conform to the spacebetween the surfaces 958 and 960, may then be moved to an operating roomfor insertion into a patient during the surgical procedure.Alternatively, the imaging of the knee portion 76 and shaping of themoveable implant 950 to the desired configuration may be performed inthe operating room as part of the surgical procedure.

When the moveable implant 950 is to be positioned in the knee portion 76of the patient's leg 70, in the manner indicated schematically in FIG.59, a limited incision is made in the knee portion of the patient's leg.The limited incision is made while the patient's leg 70 is supported inthe position shown in FIGS. 2, 3 and 25. The upper portion of thepatient's leg is supported by the leg support 80.

The incision may have a limited length, corresponding to the limitedlength of the incision 114 of FIG. 7 and be located adjacent to an edgeof the patella 120. When the implant 950 is to be positioned adjacent toa medial portion of the femur 126 and a medial portion of the tibia 214,in the manner illustrated schematically in FIG. 59, the incision 114would be located adjacent to a medial edge of the patella 120, in themanner illustrated in FIG. 6. However, it should be understood that ifthe implant 950 is to be located adjacent to a lateral portion of thefemur 126 and a lateral portion of the tibia 214, the incision 114 couldbe formed adjacent to a lateral edge of the patella 120.

Once the limited incision 114 has been formed in the manner previouslydescribed in conjunction with FIGS. 6 and 7 herein, the patella 120 maybe moved to the offset position of FIG. 8 with the inner side 122 of thepatella facing inward to facilitate utilization of an incision 114having a limited length. Once the limited incision 114 has been formed,locations in the knee portion 76 of the patient's leg 70 may beinspected utilizing an optical device similar to the endoscope 352 ofFIGS. 32 and 33. It is believed that the surgeon will bend the leg 70 ofthe patient between the flexed condition of FIG. 32 and the extendedcondition of FIG. 33 and will rotate the lower portion of the leg aboutit longitudinal central axis, in the manner indicated by the arrow 258in FIG. 25 prior to positioning of the implant 950 in the knee portion76 of the leg 70. This will enable the surgeon to detect any present orpotential interference between the implant 950 and tissue in the kneeportion 76 of the patient's leg 70.

Once this has been done, the surgeon may or may not decide to cut tissuein the knee portion 76 of the patient's leg 70 before inserting themoveable implant 950. If the surgeon elects to cut tissue in the kneeportion 76 before insertion of the implant, this cutting will berelatively minor and will not involve the femoral and tibial cutsdepicted in FIGS. 13-23 herein. This is because the moveable implant 950is to be positioned between surfaces 958 and 960 which are in theirexisting condition. Of course, eliminating the major femoral and tibialcuts illustrated in FIGS. 13-23 herein will reduce the patient'spost-operative recovery time. In addition, elimination of the majorfemoral and tibial cuts illustrated in FIGS. 13-23 enables the size ofthe incision 114 to be reduced.

Once the moveable implant 950 has been positioned between the existingsurfaces 958 and 960 on the femur 126 and tibia 214, the patella 120 ismoved from the offset position of FIG. 8 back to its normal positionrelative to the distal end portion 124 of the femur 126 and the proximalend portion 212 of the tibia 214. While the lower portion of the leg 70is suspended from the upper portion of the leg and while the upperportion of the leg is held above the support surface 64 by the legsupport 80 (FIG. 2), the incision 114 is closed in a normal manner.Prior to closing of the incision, an imaging apparatus can be utilizedto generate images of the knee portion 76 during bending of the leg 70between the flexed and extended conditions of FIGS. 32 and 33.

Any known imaging apparatus may utilized to image the knee portion 76 ofthe patient's leg 70. For example, the known C-arm fluoroscope 360 ofFIG. 34 may be utilized to generate images of the knee portion 76 of thepatient's leg 70. These images will enable the surgeon to determine themanner in which the implant 950 will move relative to the femur 126 andtibia 214 during bending of the patient's leg. Prior to closing of theincision 114, any corrective action which the surgeon may believe isnecessary can be taken to make certain that the moveable implant 950 isin the desired relationship with the femur 126 and tibia 214.

Rather than forming the incision 114 in the manner illustratedschematically in FIG. 6, the incision may be formed with an even shorterlength and a cannula, corresponding to the cannula 364 of FIG. 39,inserted into the incision. The implant 950 may be moved through theresiliently expandable cannula into the space between the existingsurfaces 958 and 960 (FIG. 59) on the femur 126 and tibia 214. Thecannula would stretch the viscoelastic material of tissues in which thevery limited incision is formed to resiliently expand the extent of theincision 114 to enable the implant 950 to be moved through the incisioneven though the moveable implant 950 is larger than the incision.

The cannula 564 (FIG. 39) through which the implant 950 (FIG. 59) ismoved into the space between the surfaces 958 and 960 is advantageouslyexpandable to accommodate the implant 950. The cannula may have any oneof the constructions previously described in conjunction with FIG. 39herein. If desired, multiple incisions, corresponding to the incisions114 and 920 of FIG. 57 may be utilized during positioning of the implant950. An expandable cannula may be associated with either or both of theincisions. Fiberoptic devices, such as an endoscope or arthroscope, maybe inserted through a very small corresponding to the incision 920 ofFIG. 57, to facilitate positioning of the implant 950. By utilizing anexpandable cannula and/or arthroscopic and endoscopic surgicalprocedures, the size of the incision 114 through which the implant 950is moved can be minimized.

The moveable implant 950 is flexible so that force transmitted betweenthe femur 126 and tibia 214 deflects the moveable implant 950. Thisresults in the moveable implant 950 being shaped by the surfaces 958 and960 on the femur 126 and tibia 214. By shaping the upper surface 952 onthe moveable implant 950 with the surface 958 on the femur 126, smoothsliding engagement is provided between the surface 958 on the femur 126and the upper surface 952 on the moveable implant 950. Similarly, thelower surface 954 on the implant 950 is shaped by the surface 960 on thetibia 214. By shaping the lower surface 954 on the implant 950 with thesurface 960 on the tibia 214, smooth sliding engagement is providedbetween the surface 960 on the tibia 214 and the lower surface 954 onthe moveable implant 950 during bending of the knee portion 76.

Shaping of the surfaces 952 and 954 on the moveable implant 950 may beaccomplished in any one of many different ways. For example, the implant950 may be formed of a material which is resiliently deflected by thesurfaces 958 and 960 on the femur 126 and tibia 214. This results in theupper surface 952 and lower surface 954 and the moveable implant 950being resiliently deflected to have a configuration corresponding to theconfiguration of the portions of the surfaces 958 and 960 which areengaged by the moveable implant during bending of the knee portion 76.During bending of the knee portion 76, the moveable implant 950 shiftsor moves relative to the surfaces 958 and 960 on the femur 126 and tibia214. During this shifting movement, the configuration of the uppersurface 952 and the lower surface 954 of the moveable implant 950 isresiliently changed by forces transmitted between the femur 126 andtibia 214 through the moveable implant 950.

Rather than having the moveable implant 950 resiliently deflected byforce transmitted between the femur 126 and tibia 214, the moveableimplant 950 may be plastically deformed by the force transmitted betweenthe femur and the tibia. Thus, the surface 958 on the femur 126 mayplastically deform the upper surface 952 on the moveable implant 950 sothat it retains a configuration corresponding to the configuration ofthe surface 958 on the femur 126. Similarly, the surface 960 on thetibia 214 may be plastically deform the lower surface 954 on themoveable implant 950 so that it maintains a configuration correspondingto the configuration of the surface 960 on the tibia 214. By plasticallydeforming the material of the moveable implant 950 with the surfaces 958and 960 on the femur 126 and tibia 214, smooth sliding engagement isobtained between the upper and lower surfaces 952 and 954 on themoveable implant 950 during bending of the knee portion 76.

Even though the upper and lower surfaces 952 and 954 on the moveableimplant 950 are either elastically or plastically shaped by the forcetransmitted between the femur 126 or tibia 214, the moveable implantwill, initially, be configured to have a shape corresponding to theexisting space between the surfaces 958 and 960. It is contemplated thatthis will result in the surfaces 952 and 954 being spaced apart bydifferent distances between different portions of the moveable implant950.

For example, the distance between the upper surface 952 and lowersurface 954 on the moveable implant 950 may be relatively large adjacentto a medial edge portion of the moveable implant 950. The distancebetween the upper and lower surfaces 952 and 954 on the moveable implant950 may be relatively small adjacent to a lateral edge portion of themoveable implant. As was previously mentioned, it is contemplated thatimages be generated of the knee portion 76 to enable the shape of theexisting space between the surfaces 958 and 960 to be determined and toenable the moveable implant 950 to be configured, outside of thepatient's body, to a configuration which generally conforms to theconfiguration of the space between the surfaces 958 and 960. Once themoveable implant 950 has been initially shaped to a configurationcorresponding to the configuration of the space between the surfaces 958and 960, the implant is positioned between the surfaces.

It is contemplated that the moveable implant 950 may be relatively thincompared to the thickness of the moveable implant illustratedschematically in FIG. 59. This would result in the upper surface 952 ofthe moveable implant 950 being spaced apart from the lower surface 954of the moveable implant by a relatively small distance. By forming themoveable implant 950 with a relatively small thickness, that is, thedistance between the upper surface 952 and the lower surface 954, theimplant will be relatively flexible. This enables the implant to bedeflected by force transmitted between the surfaces 958 and 960 on thefemur 126 and the tibia 214.

It is contemplated that a relatively flexible moveable implant 950 maybe configured so as to readily fit into an existing space in the kneeportion 76. This would result in a tendency for the moveable implant 950to become seated on the proximal end portion 212 of the tibia 214. Themoveable implant 950 would be seated on the proximal end portion 212 ofthe tibia 214 by force applied against the moveable implant by thesurface 958 on the femur 126. The lower surface of the moveable implantwould be permanently deflected to have a configuration corresponding tothe configuration of the upper surface 960 in the tibia 214. The uppersurface 952 of the moveable implant would have an overall configurationwhich may differ from the configuration of the surface 958 on the femur126. However, even though the configuration of the upper surface 952 onthe moveable implant 950 is different than the configuration on thesurface 958 on the femur 126, there would be smooth sliding engagementbetween the surface 958 on the femur 126 and the upper surface 952 ofthe moveable implant 950. The result would be that there would berelatively little movement between the lower surface 954 of the moveableimplant 950 and the surface 960 on the tibia 214 during bending of theknee portion 76. However, there would be a relatively large amount ofmovement between the upper surface 952 of the implant 950 and thesurface 958 on the femur 126. Since the moveable implant 950 would bepermanently deflected to have a configuration corresponding to the spacebetween the existing surfaces 958 and 960 on the femur 126 and tibia214, the existing surfaces 958 and 960 on the femur 126 and tibia 214would cooperate with the moveable implant 950 without inducing pain inthe knee portion 76 of the leg 70 of the patient.

It is contemplated that the moveable implant 950 may be formed of manydifferent materials. For example, the moveable implant 950 may be formedof a biological material. For example, the moveable implant 950 may beformed of allograft or autograft or xenograft. Combinations of thesegraft materials may be utilized. These graft materials may be shaped inthe manner disclosed in U.S. Pat. No. 5,888,219. The moveable implant950 may be formed of the same materials as the implant 626 of FIGS. 43and 45 if desired.

It is believed that it may be desired to form the moveable implant 950of metal. For example, the moveable implant 950 could be formed ofchromium, titanium, tantalum, zirconium or aluminum. The metal forming amoveable implant may or may not have a porous construction. The metalforming the moveable implant 950 would have a wettable surface which canbe wetted by body fluids to provide lubricity. If the moveable implant950 is formed of a porous metal, the metal may be impregnated with oneor more polymeric materials which function as lubricants.

The moveable implant 950 may be formed of a ceramic material. Theceramic material of the moveable implant may have either a porous ornon-porous construction. When the ceramic material of the moveableimplant 950 has a porous construction, it is contemplated that theopenings in the ceramic material will be filled with a lubricant tofacilitate relative movement between the surfaces 958 and 960 on thefemur 126 and tibia 214 and the surfaces 952 and 954 on the moveableimplant 950.

When the moveable implant 950 is formed of a porous material, forexample a porous metal or a porous ceramic, it is contemplated that themoveable implant could be impregnated with both a bone growth promotingmaterial and a lubricant. For example, the portion of the porousmoveable implant 950 adjacent to the upper surface 952 of the implantmay be impregnated with a lubricant. The portion of the moveable implant950 adjacent to the lower surface 954 may be impregnated with bonegrowth inductive materials.

With such a construction, the lower surface 954 of the moveable implantis configured to correspond to the configuration of the surface 960 onthe tibia 214. Therefore, the moveable implant will tend to becomeseated on the proximal end portion 212 of the tibia 214. Once this hasoccurred, the bone growth promoting materials in the porous implant 950,adjacent to the lower surface 954 of the implant, will promote growth ofbone into the moveable implant 950 to connect the moveable implant withthe tibia 214. The lubricant in the porous material adjacent to theupper surface 952 of the moveable implant 950 will minimize frictionwith the surface 958 on the femur 126 so that there will be minimaltendencies for the moveable implant 950 to move relative to the tibia214 once the moveable implant has become seated on the proximal endportion 212 of the tibia. Of course, this will facilitate the growth ofbone between the surface 960 on the proximal end portion 212 of thetibia 214 and the moveable implant 950.

The moveable implant 950 may be formed of graft materials which havebeen shaped in the manner disclosed in U.S. Pat. No. 5,888,219. Ifdesired, the moveable implant 950 may have a three dimensional scaffoldor framework structure on which graft materials are disposed. Theframework on which the graft materials are disposed may have sufficientflexibility to enable the moveable implant 950 to be flexed tocorrespond to the configuration of the surface 960 on the tibia 214 byforce applied against the upper surface 952 of the moveable implant bythe femur 126. The graft materials on the scaffold will be shaped by thesurface 958 on the femur 126 to form the upper surface 952 of theimplant with the configuration which corresponds to the configuration ofthe surface 958 on the femur.

It is contemplated that the moveable implant 950 may be formed ofmaterials which degrade with the passage of time. Thus, after theimplant 950 has been disposed in the knee portion 76 of a patient's leg70 for a predetermined period of time, for example two years, it may benecessary to replace the moveable implant 950. Due to the limitedincision required to enable the implant 950 to be positioned in the kneeportion 76, it is a relatively simple operation to replace the moveableimplant 950. The size of the incision and the trauma induced in thepatient by replacing the moveable implant 950 may be minimized by theuse of a cannula corresponding to the cannula 564 of FIG. 39. Thecannula through which the implant 950 is moved into the knee portion 76of the patient's leg may have a construction similar to the constructionillustrated in U.S. Pat. Nos. 3,811,449; 5,183,464; and/or 5,961,499.

Seating of the moveable implant on the tibia 214 may be promoted byforming the moveable implant of a hydrophilic material which absorbsbody fluids and expands. When the implant 950 of hydrophilic material ispositioned in the space between the surfaces 958 and 960 on the femur126 and tibia 214, the hydrophilic material of the implant will absorbbody fluids and expand to fully occupy the space. This will result inthe lower surface 954 of the moveable implant 950 being pressed firmlyagainst the surface 960 on the tibia 214. Similarly, the upper surface952 on the moveable implant 950 will be pressed against the surface 958on the femur 126 as the moveable implant absorbs body fluids andexpands. This results in the moveable implant 950 expanding in such amanner as to change the configuration of the moveable implant to theconfiguration of the space between the surfaces 958 and 960 on the femur126 and tibia 214.

The hydrophilic material of the moveable implant 950 may be a polymericmaterial which is either a copolymer or a dipolymer. The hydrophilicmaterial may contain petroylglupamic acid, carboxymethylcellulose, acollagen or polylactide. The hydrophilic material may be a ceramic thatis found in hydroxyapatite composites with polyethylene, polylactide orpolyhydroxybutyrate. Of course, the moveable implant 950 could be formedof other known hydrophilic materials which attract body liquid under theinfluence of molecular attraction and establishes molecular linkageswith the body liquid. The hydrophilic material may be disposed on aframe work or base which is formed of a non-hydrophilic material such asa porous metal.

It should be understood that the patient's leg 70 is supported in amanner previously explained herein in conjunction with FIGS. 2 and 3.The improved drape system 100 of FIGS. 4 and 5 may be utilized duringsurgery in which the moveable implant 950 is positioned in the kneeportion 76 of the patient's leg 70. The patient's leg 70 may be moved inthe manner schematically by arrows in FIG. 25 to enable a surgeon tomake certain that the moveable implant 950 cooperates with the femur 126and tibia 214 in a desired manner. The articular surface 122 on thepatella 120 may be repaired in the manner indicated schematically inFIGS. 35 and 36, contemporaneously with positioning of the moveableimplant 950 in the knee portion 76. One or more expandable devices,similar to the expandable devices 720, 722 and 730 of FIGS. 51 and 52may be utilized to facilitate positioning of the moveable implant 950 inthe knee portion 76 of a patient's leg 70. It should be understood thatany of the features previously described in conjunction with FIGS. 1-58herein could be utilized, if desired, in association with the moveableimplant 950.

Moveable Inlay

In the embodiment of FIG. 59, the moveable implant 950 is positioned inengagement with existing surfaces 958 and 960 on the femur 126 and tibia214. In the embodiment illustrated in FIG. 60, a moveable implant 970 ispositioned in a recess 972 formed in a medial portion of the proximalend portion 212 of the tibia 214. The recess 972 may be relativelyshallow and formed with a minimum or no cutting away of bone from theproximal end portion 212 of the tibia 214. The recess may be formed bycutting away cartilage and/or other material disclosed on the proximalend portion 212 of the tibia 214. Depending upon the condition of theproximal end portion 212 of the tibia 214, the bone may or may not becut away to form the recess 972. Thus, the recess may be formed intissues, such as fibrous tissues, associated with the end portion of thebone at the proximal end portion of the tibia 214.

The moveable implant 970 may be held in position relative to theproximal end portion 212 of the tibia 214 by engagement with the recess972. If this is done, tissue growth promoting materials and/or materialswhich promote biological resurfacing may be provided in the moveableimplant 970. These materials would promote the growth of tissue adjacentto the proximal end portion 212 of the tibia 214 into the moveableimplant 970. The biological resurfacing materials would promote thegrowth of naturally occurring tissues, which were not removed to formthe recess 972, into the moveable implant 970. Thus, cartilage tissueslocated adjacent to the peripheral aspect of the proximal end portion212 of the tibia 214 would grow into the moveable implant 970.

It should be understood that the recess 972 may have a lower surfaceformed by the existing surface 960 of the tibia and side surfaces formedby fibrocartilage which extends around the periphery of the moveableimplant 970. It is believed that it will be desired to position themoveable implant 970 in the recess 972 without anchoring the moveableimplant to the tibia 214. However, if desired, an adhesive such asfibrin could be utilized to connect the moveable implant with theexisting surface 960 on the proximal end portion 212 of the tibia. Themoveable implant 970 may have any one of the constructions previouslydescribed in conjunction with the implant 640 of FIGS. 46 and 48 or themulti layered implant 670 of FIG. 49.

Multi Component Moveable Implant

The moveable implant 950 of FIG. 59 is formed as one piece. In theembodiment of the invention illustrated in FIG. 61, the moveable implant980 is formed with a plurality of pieces. The moveable implant 980 isdisposed between a medial portion of the distal end portion 124 of afemur 126 and a medial portion of the proximal end portion 212 of atibia 214. The moveable implant 960 is positioned between an existingsurface 958 on the femur 126 and an existing surface 960 on the tibia214. The moveable implant 980 includes an upper section 982 and a lowersection 984. The upper section 982 has an upper surface 988 whichengages the existing surface 958 on the distal end portion 124 of thefemur 126. The upper section 982 of the moveable implant 980 has a lowersurface 990 which engages the lower section 984 of the moveable implant980.

The lower section 984 of the moveable implant 980 has a lower surface994 which engages the existing surface 960 on the proximal end portion212 of the tibia 214. In addition, the lower section 984 of the implant980 has an upper surface 986 which engages a lower surface 990 on theupper section 982 of the moveable implant 980.

The surfaces on the moveable implant 980 which engage existing surfaceson the femur 126 or tibia 214 are shaped to conform to the configurationof the existing surfaces on the femur and the tibia. To enable thesurfaces on the moveable implant to be shaped to conform to theconfiguration of existing surfaces on the femur 126 and tibia 214,images of the femur and tibia are generated utilizing known imagingapparatus, such as an MRI, X-ray, or fluoroscope. These images areutilized to determine the configuration of the existing surface 958 onthe femur 126 and the existing surface 960 on the tibia 214. The uppersurface 988 on the upper section 982 of the moveable implant 980 is thenshaped to a configuration corresponding to the configuration of theexisting surface 958 on the femur 156. The lower surface 994 on thelower section 984 of the moveable implant 980 is shaped to aconfiguration corresponding to the configuration of the existing surface960 on the tibia 214. By shaping the upper and lower surfaces 988 and994 on the implant 990 to conform to the shape of the existing surfaces958 and 960 on the femur 126 and tibia 214, the upper and lower sections982 and 984 tend to seat themselves on the femur 126 and tibia 214.Thus, the upper surface 988 on the upper section 982 of the moveableimplant 980 becomes seated against the existing surface 958 on the femur126 under the influence of force transmitted between the existingsurface 958 on the femur and the upper surface 988 on the upper section982 of the moveable implant 980. Similarly, the lower surface 994 on thelower section 984 of the implant 980 becomes seated against the existingsurface 960 on the tibia 214 under the influence of force applied to theupper surface 996 on the lower section 984 of the moveable implant 980by the upper section 982 of the moveable implant.

The lower surface 990 on the upper section 982 of the moveable implant980 and the upper surface 996 on the lower section 984 of the moveableimplant 980 are shaped to promote the desired articulation in the kneeportion 76 of the leg 70. Once the two sections 982 and 984 of themoveable implant 980 have been positioned between the existing surfaces958 and 960 on the femur 126 and tibia 214, relative movement occurswhere the lower surface 990 on the upper section 982 of the moveableimplant 980 engages the upper surface 996 on the lower section 984 ofthe moveable implant. This tends to minimize any pain or discomfortresulting from defects in the existing surfaces 958 and 960 on the femur126 and tibia 214 during bending of the knee portion 76.

The upper section 982 and lower section 984 may be formed of the samematerials or any combination of the same materials as previouslydescribed in conjunction with the moveable implant 950 of FIG. 59.Although the upper section 982 and lower section 984 of the moveableimplant 980 are fanned of the same material, it is contemplated that theupper section 982 could be formed of a material which is different thanthe material forming the lower section 984 of the moveable implant 980.

The moveable implant 980 will be positioned in the space between theexisting surfaces 958 and 960 on the femur 126 and tibia 214 in themanner previously discussed in conjunction with the embodiment of theinvention illustrated in FIG. 59. Thus, the patient's leg will besupported in the orientation illustrated in FIGS. 2 and 3 during themaking of a limited incision along one side of the patella 120 in themanner illustrated in FIG. 6. The patella 120 may then be offset to oneside. Alternatively, the patella may remain in its initial position orbe offset just slightly to provide sufficient space to insert themoveable implant 980. It is contemplated that the knee portion 76 willbe inspected utilizing fiberoptic devices similar to the endoscope 352of FIGS. 32 and 33. An expandable cannula corresponding to the cannula364 of FIG. 39, may be inserted into the incision and the endoscopeand/or the moveable implant 980 inserted into the knee portion 76through the expandable cannula.

Moveable Implant with Anchored Section

In the embodiment of the invention illustrated in FIG. 61, the moveableimplant 980 has upper and lower sections 982 and 984 which are moveablerelative to each other and relative to the femur 126 and tibia 214. Inthe embodiment of the invention illustrated in FIG. 62, a moveableimplant 1002 has a section which is fixedly connected with a bone in theknee portion 76 of the patient. In the embodiment of the inventionillustrated in FIG. 62, the moveable implant 1002 includes an uppersection 1006 and a lower section 1008. The upper section 1006 of theimplant 1002 is freely moveable relative to the femur 126. The lowersection 1008 of the moveable implant 1002 is anchored to the tibia 214.Thus, the upper section 1006 of the moveable implant 1002 is freelymoveable relative to the existing surface 958 on a medial portion of thedistal end portion 124 of the femur 126. The upper section 1006 is alsofreely moveable relative to the tibia 214. However, the lower section1008 of the moveable implant 1002 is anchored to the tibia 214 by a keelor projecting section 1012. The projecting section 1012 extends throughthe existing surface 960 on a medial portion of the proximal end portion212 of the tibia 214.

The upper section 1006 and lower section 1008 of the moveable implant1002 are formed of the same material as previously discussed inconjunction with the moveable implant 950. The upper and lower sections1006 and 1008 of the moveable implant 1002 are positioned in the spacebetween the existing surfaces 958 and 960 through a cannula whichcorresponds to the cannula 564 of FIG. 39. The cannula extends into alimited incision and is resiliently expandable to stretch theviscoelastic body tissue in which the limited incision is formed toenable the moveable implant 1002 to be moved through the cannula intothe space between the existing surfaces 958 and 960 on the femur 126 andtibia 214.

Although the lower section 1008 of the moveable implant 1002 has beenillustrated in FIG. 62 as being anchored to the tibia 214 and the uppersection 1006 freely moveable relative to the femur 126, this could bereversed if desired. Thus, the upper section 1006 of the moveableimplant 1002 could be anchored to the femur 126. If this was done, thelower section 1008 of the moveable implant 1002 would be freely moveablerelative to the tibia 214.

Securing Moveable Anchor

In the embodiment of the invention illustrated in FIG. 59, the moveableimplant 950 is freely moveable relative to the existing surfaces 958 and960 on the femur 126 and tibia 214. In the embodiment of the inventionillustrated in FIG. 63, a moveable implant 1020 is connected with themedial collateral ligament 1022. Although the moveable implant 1020 isdisposed between and is freely moveable relative to existing surfaces958 and 960 on the femur 126 an the tibia 214, the connection betweenthe moveable implant 1020 and the medial collateral ligament 1022 limitsthe range of movement of the moveable implant 1020 relative to theexisting surface 958 on a medial portion of the distal end portion 124of the femur 126. Similarly, the connection between the moveable implant1020 and the medial collateral ligament 1022 limits the range ofmovement of the implant 1020 relative to the existing surface 960 on amedial portion of the proximal end portion 212 of the tibia 214.

The moveable implant 1020 has the same construction as the moveableimplant 950 of FIG. 59. However, the moveable implant 1020 is providedwith a small passage or opening which enables a suture 1026 to be usedto interconnect the moveable implant 1020 and the ligament 1022. Thesuture 1026 extends through the opening in the moveable implant 1020 andextends around the ligament 1022. The suture 1026 holds the moveableimplant 1020 in engagement with the ligament 1022. This results in aside surface 1030 on the moveable implant 1020 being held in intimateapposition with the ligament 1022. Due to engagement of the side surface1030 on the moveable implant 1020 with the ligament 1022, tissue cangrow from the ligament into the moveable implant 1020 to furtherinterconnect the ligament and the movable implant.

It is contemplated that the moveable implant 1020 will have aconstruction which promotes the in growth of tissue from the ligament1022 into the implant. Thus, the moveable implant 1020 may have a porousscaffold on which tissue growth inductive factors are disposed. Forexample, the moveable implant 1020 could be formed of porous tantalum.The porous tantalum scaffold could contain collagen, fibrin, progenitorcells and/or tissue inductive factors. Of course, other known materialswhich promote biological resurfacing could be provided on the porousmetal scaffold of the moveable implant 1020 if desired.

Although one specific construction of the moveable implant 1020 has beendescribed, it is contemplated that the moveable implant 1020 could havemany different constructions. For example, the moveable implant 1020could have any one of the constructions and be formed of any one or moreof the materials previously described in conjunction with the moveableimplant 950.

It is contemplated that the patient's leg 70 may be in the positionillustrated in FIGS. 2 and 3 during positioning of the moveable implant1020 in the space between the existing surfaces 958 and 960 on the femur126 and tibia 214. The upper portion of the patient's leg 70 may besupported above the support surface 64 (FIG. 2) by the leg support 80.The drapery system 100 of FIGS. 4 and 5 may advantageously be utilizedduring positioning of the moveable implant 1020 to provide a sterilefield.

Connection of Moveable Implant with Soft Tissue

In the embodiment of the invention illustrated in FIG. 59, the moveableimplant 950 is freely moveable relative to the existing surfaces 958 and960 on the femur 126 and tibia 214. In the embodiment of the inventionillustrated in FIG. 63, the moveable implant 1020 is connected with theligament 1022 to limit the range of movement of the moveable implant1020. In the embodiment of the invention illustrated in FIG. 64, amoveable implant 1040 is connected with soft tissue other than theligament 1022 of FIG. 63. Rather than being connected with the softtissue by single suture 1026 in the manner illustrated in FIG. 63, themoveable implant 1040 is connected with soft tissue in a plurality oflocations by a plurality of sutures.

The moveable implant 1040 (FIG. 64) has the same construction as themoveable implant 950 of FIG. 59. The moveable implant 1040 is positionedbetween existing surfaces 958 and 960 (FIG. 59) on a femur 126 and tibia214 in the same manner as is illustrated schematically in FIG. 59 forthe moveable implant 950. The moveable implant 1040 is moved intoposition between the existing surfaces on a femur and a tibia in thesame manner as previously explained in conjunction with the moveableimplant 950 of FIG. 59. Thus, the moveable implant 1040 of FIG. 64 ismoved into a position between existing surfaces 958 and 960 on a femurand tibia through a limited incision and a resiliently expandablecannula corresponding to the cannula 564 of FIG. 39.

In accordance with one of the features of this embodiment of theinvention, a plurality of connections 1044 are provided between theperiphery of the moveable implant 1040 and soft tissue 1046. Althoughmany different soft tissues in the knee portion 76 of a patient's legmay be connected with the moveable implant 1040 by connections 1044, inthe embodiment of the invention illustrated in FIG. 64, the moveableimplant 1040 is connected with the joint capsule in the knee portion 76of the patient's leg 70. The joint capsule extends around and enclosesthe knee joint. Therefore, the connections 1044 can be formed betweenthe moveable implant 1040 and the soft tissue of the joint capsule 1046at a plurality of locations in the manner illustrated in FIG. 64.

By providing anterior and posterior connections 1044 with the softtissue of the joint capsule 1046, the moveable implant 1040 is heldagainst excessive movement in either a posterior or anterior direction.Similarly, the connections 1044 between the moveable implant 1040 andthe medial portion of the soft tissue or joint capsule 1046 holds themoveable implant 1040 against excessive movement in either the medial orlateral direction. The connections 1040 may initially be formed bysutures.

Although the range of movement of the moveable implant 1040 relative tothe femur 126 and tibia 214 (FIG. 59) is limited by the connections 1044(FIG. 64), the moveable implant 1040 is freely moveable relative to theexisting surfaces 958 and 960 (FIG. 59) on the femur 126 and tibia 214within the range of movement established by the connections 1044 withthe soft tissue or joint capsule 1046.

Tissue inductive growth factors are provided on the moveable implant1040. The tissue inductive growth factors promote a growth of the softtissue onto the moveable implant 1040. It is contemplated that themoveable implant 1040 will have a porous platform in which the tissuegrowth inductive factors are disposed. This will promote a growth of thesoft tissue or joint capsule 1046 into the moveable implant 1040 toassist the sutures at the connections 1044 in interconnecting themoveable implant 1040 and the soft tissue or joint capsule 1046.

Thus, the connections 1044 between the moveable implant 1040 and thesoft tissue 1046 is initially established by sutures which extendbetween the moveable implant 1040 and the soft tissue or joint capsule1046. With the passage of time, tissue grows from the soft tissue orjoint capsule 1046 into the periphery of the moveable implant 1040 tofurther interconnect the moveable implant 1040 and the soft tissue. Thesutures which initially form the connections 1044, hold the periphery ofthe moveable implant 1040 in engagement with the soft tissue 1046. Dueto the intimate apposition of the moveable implant 1040 with the softtissue or joint capsule 1046 and the tissue growth promoting factors inthe moveable implant 1040, growth of the soft tissue or joint capsule1046 into the periphery of the moveable implant 1040 is promoted.

Molded Implant

In the embodiment of the invention illustrated in FIGS. 65 and 66, animplant 1060 is molded onto an existing surface 960 on the proximal endportion 212 of the tibia 214. The implant 1060 is formed of bone cementwhich is held in place by a retainer or dam 1064 which extends around amedial portion of the proximal end portion 212 of the tibia 214. The damforms a compartment which is filled with the bone cement. As the bonecement hardens, the femur 126 (FIG. 59) is moved relative to the tibia214 to impart a desired configuration to the bone cement.

Once the bone cement has hardened, the retainer or dam 1064 may beremoved. The bone cement then forms an implant which is disposed on theexisting surface 960 of the tibia 214. The bone cement is connected withexisting surface 960 of the tibia 214 by adhesion between the implant1060 and the existing surface 960 of the tibia 214. It is contemplatedthat a releasing agent could be mixed with the bone cement which is usedto form the implant 1060 so that the implant would not adhere to theexisting surface 960 of the tibia 214. This would result in the implant1060 being freely moveable relative to both the tibia 214 and the femur126 in the same manner as in which the moveable implant 950 is freelymoveable relative to the femur 126 and tibia 214.

Deformity Correction

The moveable implants of FIGS. 59-66 are utilized to affect aresurfacing of joint surfaces to minimize pain resulting from defectivejoint surfaces. The moveable implants of FIGS. 59-66 are notparticularly effective in correcting deformities in the femur 126 and/ortibia 214. Thus, the moveable implant 950 (FIG. 67) is positionedbetween the femur 126 and tibia 214 to compensate for defects in theexisting surfaces 958 and 960 on the femur 126 and tibia 214. It iscontemplated that other devices will have to be utilized to compensatefor bone deformities. The devices which are utilized to compensate forbone deformities may be positioned in the femur 126 and/or tibia 214.

The devices which compensate for bone deformities may have aconstruction similar to the construction of any one of the devicesdisclosed in U.S. Pat. No. 6,086,593. Of course, other known devicescould be utilized to correct bone deformities if desired.

One specific device which may be utilized to correct bone deformities isa wedge member 1080 (FIG. 67). The wedge member 1080 is formed of arelatively hard rigid material. The wedge member 1080 is capable oftransmitting force between upper and lower portions of a bone, such asthe tibia 214. The wedge member 1080 may be hollow and have acompartment which is filled with bone growth inductive material. Thewedge member may be formed of a suitable rigid material, such astantalum or stainless steel. Alternatively, the wedge member 1080 couldbe formed of a biodegradable material. It is contemplated that the wedgemember 1080 may be formed of human bone.

When the wedge member 1080 is to be positioned in the tibia 214, a sawcut is made to form a slot at the location where the wedge member 1080is to be installed. The saw cut and resulting slot extend only part waythrough the tibia 214. The wedge member 1080 is then moved into theslot. As the wedge member is forced into the slot, the wedge memberpivots an upper portion of the tibia 214 in a counter-clockwisedirection (as viewed in FIG. 67) relative to a lower portion of thetibia to correct a deformity in the tibia or to compensate for adeformity in the femur 126.

Although the wedge member 1080 has been illustrated in FIG. 67 as beinginstalled in the tibia 214, it is contemplated that the wedge membercould be installed in the femur 126 if desired. Although the wedgemember 1080 has been illustrated in FIG. 67 as being installed in amedial portion of the tibia 214, the wedge member 1080 could beinstalled in a posterior, anterior or lateral portion of the tibia ifdesired. The wedge member 1080 has the same construction and cooperateswith the femur in the same manner as is disclosed in the aforementionedU.S. Pat. No. 6,086,593.

It is contemplated that the patient's leg 70 will be in the positionillustrated in FIGS. 2 and 3 during installation of any one of theimplants illustrated in FIGS. 59-66. However, the implants could bepositioned in the patient's leg with the patient's leg in a differentorientation if desired. Thus, any one of the implants of FIGS. 59-66could be placed in the patient's leg with the patient's leg in eitherthe flexed or extended orientation illustrated in FIG. 1.

The foregoing description of the moveable implants of FIGS. 59-66 hasbeen in conjunction with the knee portion 76 of a patient's leg 70.However, it is contemplated that the implants will be used inassociation with other joints in a patient's body. For example, any oneof the implants of FIGS. 59-66 could be utilized in association with aglenoid joint. Alternatively, any one of the implants could be used inassociation with an ankle, wrist or elbow joint. It is contemplated thatany one of the many different features of the present invention may beutilized separately or in association with the implants illustrated inFIGS. 59-66 and that the implants may be used in association with anydesired joint in a patient's body.

In-Situ Bone Removal

As previously detailed, one aspect of the present invention is theperformance of all or a portion of a surgical procedure through acannula. FIGS. 68-74 show one embodiment of this aspect as applied tothe hip joint. Access to acetabulum 1100 and proximal portion of femur1102 may be obtained through a cannula 1104. Cannula 1104 is insertedinto incision 1106, which is formed with a relatively short length(generally less than 10 cm in length) in the manner previously describedherein. Cannula 1104 has an initial size, illustrated in FIG. 68, whichstretches the viscoelastic tissue around the hip joint. Therefore,initial insertion of cannula 1104 into incision 1106 is effective toexpand the incision.

FIG. 68 shows one manner in which guidance of the cannula (and anysubsequent surgical implement going therethrough) to the desiredlocation can be facilitated. A guide wire 1108 having a sharp tip isdriven through femur 1102 and pinned to bone. Although guide wire 1108is shown pinned to acetabulum 1100, guide wire 1108 can be pinned tofemur 1102, as discussed below. Pinning guide wire 1108 to bone helps toensure that the location of cannula 1104 remains relatively constantduring the surgical procedure.

A pilot hole can be created through femur 1102 to help insert guide wire1108. Additionally, the creation of this pilot hole and/or the insertionof guide wire 1108 can be done under imaging guidance, such asfluoroscopy. Additionally, the proximal end of guide wire 1108 orcannula 1104 (FIG. 69) can include an IR reflector 1109 for use with acomputer surgical navigation system to monitor the location of guidewire 1108. As is well known, IR reflector 1109 can alternatively be anelectromagnetic radiation transmitter or receiver depending on thespecific computer surgical navigation system.

Cannula 1104 is advantageously expandable to further stretch theviscoelastic tissue. Of course, expanding cannula 1104 increases thesize of a passage 1110 formed by an inner side 1112 of cannula 1104,thereby enabling a relatively large object to pass through the passage.Thus, cannula 1104 may be expanded to facilitate movement of surgicalimplements, such as implants and instruments through the cannula.

It is contemplated that expandable cannula 1104 may have many differentknown constructions. The illustrated cannula 1104 is formed ofelastomeric material and has the same construction as disclosed in U.S.Pat. No. 6,338,730. It should be understood that cannula 1104 could havea different construction, for example, a construction similar to theconstructions disclosed in U.S. Pat. No. 3,811,449 or 5,183,464.

Cannula 1104 can be expanded in many different ways other than under theinfluence of force transmitted directly to the cannula from an objectmoving through the cannula. Cannula 1104 may be expanded by insertingtubular members into the cannula. Alternatively, fluid pressure could beused to expand cannula 1104 in the manner disclosed in theaforementioned U.S. Pat. No. 6,338,730.

By utilizing expandable cannula 1104 or the expandable pneumaticretractors previously disclosed, force can be applied against oppositesides of incision 1106 to stretch the viscoelastic material disposedadjacent to opposite sides of the incision. This will result in therelatively small incision 1106 being expanded to accommodate relativelylarge surgical instruments and/or implants.

Once cannula 1104 is inserted, guide wire 1108 can be removed ifdesired. Alternatively, guide wire 1108 can be used to direct insertionof other surgical implements. Regardless of whether guide wire 1108 isremoved, cannula 1104 can be moved or pivoted about incision 1106 sothat its location can be varied. This is particularly useful, forexample, if the area surrounding the surgical site needs to be accessed.

Although a single incision 1106 is illustrated in FIG. 68, it iscontemplated that a plurality of incisions could be provided. Thus, asmall incision may be spaced from the incision 1106 to enable asuctioning tool to be moved into the hip joint along a path which isspaced from and may be transverse to a path along which a cutting toolis moved through the incision 1106. A second cannula, which is smallerthan the cannula 1106, may be utilized with the second incision.

If desired, tissue retractors and/or dissectors can be used to createspace between the soft tissue and the bones of the hip joint. Prior artmechanical dissectors and retractors can be used. It is alsocontemplated that fluid operated retractors, expanders, and/ordissectors may be used to retract, expand or dissect body tissue. Forexample, retractors having a construction similar to any one of theconstructions disclosed in U.S. Pat. No. 5,197,971 may be utilized torelease tissue at locations spaced from incision 1106. When tissue is tobe released at locations where there is limited accessibility fromincision 1106, a device similar to any one of the devices disclosed inU.S. Pat. No. 5,295,994 may be utilized. It is believed that devicessimilar to those disclosed in U.S. patent application Ser. No.09/526,949 filed Mar. 16, 2000 may be used in ways similar to thosedisclosed therein to move and/or release body tissue.

As shown in FIG. 69, a fluid operated device 1114 is inserted throughcannula 1104 so that a bladder 1116 is placed between soft tissue 1117and acetabulum 1100 and femur 1102. Bladder 1116 is inflated by fluidintroduced via tubing 1118 to move soft tissue 1117 relative toacetabulum 1100 and femur 1102. Fluid operated device 1114 may be formedof biodegradable or non-biodegradable material. If bladder 1116 andtubing 1118 are formed of a biodegradable material, they need not beremoved prior to closing of incision 1106.

In the case of a hip replacement surgery (total or partial), a reamer istypically used to create a uniform cavity for the acetabular componentand/or an oscillating blade is typically used to remove a portion of thefemoral head so that the femoral component can be received in themedullary canal of the femur. In this regard, compact cutting tools,similar to those utilized for arthroscopic, endoscopic, or fiber opticassisted surgery may be at least partially moved through passage 1110 toaffect in situ removal of bone. The cutting tools may have aconstruction similar to the construction illustrated in U.S. Pat. No.5,540,695 or 5,609,603. Alternatively, the cutting tools may have aconstruction similar to the construction disclosed in published U.S.Patent Application No. 2002/0055755 A1.

U.S. Pat. No. 5,269,785 also discloses a tissue removal system andmethod that can be used with the limited incision system according tothe present invention. This patent discloses a device with a flexibleshaft and a controllable tip. Furthermore, the device can be singlelumen or multi-lumen, with a cannula if desired. The cutting tip can becontrolled via valves, pneumatics, radio control, fiberoptic control,electric wire control, cable control, or pneumatic control. Multiplemovable segments or a single movable segment can provide theflexibility. Joints can be provided between rigid sections. Theflexibility and controllability are particularly useful in limitedincision procedures. For example, the device can be bent over a60-90.degree. angle, and then selectively remove osteophytes at the edgeof the tissue without damaging the associated tissue. Furthermore, theoption of suction provides for tissue removal and the option ofirrigation minimizes heat necrosis in the limited operative space.

The reaming of the acetabulum can be done in a single pass with a singlereamer, or a plurality of progressively larger reamers can be used.Guide wire 1108 is particularly helpful with multiple reamers since thelocking of guide wire 1108 with respect to acetabulum 1100 helps ensurethat each reamer is reaming about the same central axis.

FIGS. 70A-70B show another embodiment of a tissue removing surgicalinstrument particularly useful for minimally invasive hip replacementsurgeries. FIG. 70A shows tissue removing surgical instrument 1120 in aretracted position so that instrument 1120 can move freely within lumen1110 of cannula 1104. Instrument 1120 is provided with a cannulation1122 along a shaft 1123 so that instrument 1120 can be moved along guidewire 1108. Upon activation, distal end 1124 of instrument 1120 assumesthe shape shown in FIG. 70B. Concave underside 1126 of the cup-shapeddistal end 1124 has at least one cutting surface 1128 so that rotationof instrument 1120 in conjunction with retrograde movement of instrument1120, i.e. movement in the direction of arrow 1130 (FIG. 71), causesremoval of the bone forming the head of femur 1102.

Convex top side 1132 of the cup-shaped distal end 1124 has at least onecutting surface 1134 (shown in the form of gratings typical of prior artacetabular reamers) so that rotation of instrument 1120 in conjunctionwith antegrade movement of instrument 1120, i.e. movement in thedirection of arrow 1136 (FIG. 72), causes reaming of acetabulum 1100.Instrument 1120 can be provided with irrigation and suctioningcapacities, as taught in published U.S. Patent Application No.200210055755 A1 to minimize heat necrosis and aid in the evacuation ofthe removed bone. Alternatively, a separate suctioning, and if desired,irrigation device, can be used. The separate device(s) can extendthrough cannula 1104 or an additional cannula.

Activation of instrument 1120 can occur in a number of different ways.For example, rotational movement of instrument 1120 alone can causeinstrument 1120 to go from the retracted (FIG. 70A) to the extendedposition (FIG. 70B). U.S. Pat. No. 5,445,639 teaches one such rotationalmechanism. Alternatively, fluid pressure, cable means, or other similarmechanisms can be used for activation.

After removal of the head of femur 1102 and reaming of acetabulum 1100,the cutting tool or tools can be withdrawn from the hip joint. In thecase of instrument 1120, instrument 1120 can be pulled back throughpassage 1110, with distal end 1124 in the retracted position, or in theexpanded position if the diameter of passage 1110 permits and thesurgeon so desires. Alternatively, distal end 1124 can be separated fromthe rest of instrument 1120, for example by cutting off and removalthrough a separate incision.

It should be noted that the reaming of acetabulum 1100 and removal ofthe head of femur 1102 can be done with minimal, i.e. subluxation, or nodislocation of the hip joint. As previously noted, access to the jointspace can be increased by movement of cannula 1104. Additionally, thejoint space can be manipulated remotely. For example and as shown inFIG. 68, an elongate member 1138, such as a Schanz screw, can beinserted through a stab wound and attached to femur 1102. Elongatemember 1138 can be used as a lever arm to increase the access to the hipjoint. As a result of the reduction or elimination of dislocation, theinteroperative strain on the soft tissue surrounding the hip joint isminimized. Any damage or cutting of soft tissue is also minimized. Thesefeatures limit post-operative pain and lead to quicker surgicalrecovery.

The present invention also envisions insertion of some or all of theimplant components through cannula 1104. This concept will beillustrated with a description of the procedure for an acetabularcomponent. An analogous procedure for the femoral component can be usedand a procedure for use with the knee has been described above. FIG. 73shows the backing 1140 (typically made of a metal) of an acetabularcomponent being inserted. Cannula 1104 is in an expanded state toaccommodate the backing 1140. Alternatively, a larger non-expandablecannula could be used. Preferably, guide wire 1108 is the same guidewire that was used for cannula 1104 and tissue removing instrument 1120.This helps to ensure that backing 1140 is implanted at the same locationthat the reaming occurred.

Guide wire 1108 can be removed so that a standard liner or insert(typically made of polyethylene) can be used in conjunction with backing1140. Alternatively and as shown in FIG. 74A, an insert 1142 having abore 1144 can be used so that insert 1142 can slide over guide wire 1108in a manner similar to backing 1140. FIG. 74B shows another design foran insert 1146 that has a bore 1148 so that insert 1146 can slide overguide wire 1108. One different between insert 1142 and insert 1146 isthe location of bore 1144 compared to bore 1148. Bore 1148 is placed inan area where no articulation with the ball of the femoral componentoccurs. As a result, the tolerances for the edges surrounding bore 1148are not a significant concern for the generation of wear debris.Regardless of the location, the bore can be sealed, for example with anadhesive, to help contain any wear debris and minimize migration.

Other acetabular designs can be used. For example, the backing and lineracetabular components can be bonded together, either inside or outsideof the patient. The portions may be bonded together by the applicationof energy in any one of many different forms, such as ultrasonic energyand heat. The present invention also envisions the application of theprinciples described and shown in FIGS. 68-74 to other locations in thebody. Examples include the knee, the shoulder (both the glenoid andhumeral components), the joints of the hand and wrist, the joints of thefoot and ankle, and the spine. With respect to the spine, suitableprocedures include any procedure involving the disc space and/or thevertebra, such as fusions, pedicle screw insertions, cages, or otherimplants.

In knee replacement procedures, in situ reaming of the patella as wellas the condyles of the femur and tibia can be performed. Specifically, aguide wire is placed over the condyles and reaming occurs over thisguide wire using a mill or a cutting saw. The patella could be removedin a similar fashion with a retrograde reamer directed by a guide wire.As previously described, the milling/cutting tools could be used inconjunction with jigs that allow a plurality of intersecting straightcuts or a smooth arc cut. The jig can be mounted on the medial orlateral side. If desired, the cutting of the femur and tibia can be doneusing a limited incision approach and the implantation of the femur,tibia, and/or patella components can be done through a larger incision.

Lateral/Medial Approach to Knee Replacement

As previously discussed (see, e.g. FIG. 54 and associated text), oneaspect of the present invention includes a medial or lateral approach tojoint replacement and other surgeries near a joint. FIGS. 75-77 show oneembodiment of this aspect. FIG. 75 shows that femoral medial epicondyle1150 is osteotomized or cut from distal end 1152 of femur 1102. Thisosteotomy removes the superior attachment point of medial collateralligament 1154 so that the joint space between femur 1102 and tibia 1156can be pivoted open and accessed from the medial side. As analternative, the tibial medial epicondyle 1158 could be osteotomized toseparate the inferior attachment point of medial collateral ligament1154 so that the joint space could be accessed from the medial side.Additionally, either the femoral or tibial lateral epicondyle 1160, 1162could be osteotomized to separate one of the attachment points oflateral collateral ligament 1164. Furthermore, medial collateralligament 1154 or lateral collateral ligament 1164 can be cut without theneed for removal of bone, if desired. However, as healing a bone/boneinterface can be easier than healing a ligament/ligament interface,separate of the ligament through an osteotomy may be preferable.

In this regard, FIG. 77 shows that femoral medial epicondyle 1150 can bereattached to distal end 1152 of femur 1102 with a screw 1166 or staple.As an alternative to screw 1166, any method suitable for reattaching onepiece of bone to another piece of bone can be used.

By accessing the joint space from a side medial or lateral to thecenterline of the joint, the incision can be made shorter, as previouslydiscussed. Additionally, and as previously discussed, a medial orlateral incision stretches less than a direct anterior incision. Withrespect to the knee joint in particular, when an incision is directlyover the patella, the incision length increases 30% from 0.degree.extension to 120.degree. flexion. If the incision is shifted morelaterally or medially, such as over the medial collateral ligament, theincision only lengthens approximately 12% from 0.degree. extension to120.degree. flexion. There is less stress on the soft tissue andtherefore less scarring and less postoperative pain. Also by going moremedial or lateral with the incision there is less damage and lessdisruption of the quadriceps mechanism. Furthermore, patella 1168 tendsto naturally move toward the pivot location when the joint space ishinged open from either a medial or lateral approach. The naturalmovement of patella 1168 allows anterior access to the joint spacewithout the need to evert patella 1168. However, patella 1168 can beminimally subluxed and/or everted to increase the exposure of the jointspace, if desired.

Returning to the embodiment in FIGS. 75-77, any desired procedure can beperformed within any joint space. Thus, the medial or lateral approachcan be applied, for example, to the hip, shoulder, the joints of thehand and wrist, the joints of the foot and ankle, and the spine.However, this embodiment is particularly useful for knee jointreplacement surgeries. FIGS. 78 and 79 show one implant that can be usedin this regard. In general, prior art knee prostheses for partially ortotally replacing a knee joint include a femoral component forattachment to the distal end of the femur and a tibial component forattachment to the proximal end of the tibia. The tibial componenttypically includes a base or tray that is implanted in the tibia and aninsert or meniscal plate placed on the face of the tray for articulatingwith the condyles of the femoral component. The tray often includes akeel or stem that inserts in the tibia to provide stability.

In contrast, tibial tray 1170 is a modular unit comprising a base 1172and a keel 1174. An inferior surface 1176 of tibial tray 1170 issubstantially flat so that tibial tray 1170 can be slid into positionfrom the lateral or medial side onto previously cut or milled tibia1156. A side cutting jig analogous to that shown in FIG. 54 or otherside cutting or milling techniques can advantageously be used to preparetibia 1156 for receiving tibial tray 1170. Tibial tray 1170 is providedwith openings 1178 that extend from a superior surface 1180 throughinferior surface 1176. Openings 1178 are sized to receive keel 1174. Asshown, keel 1174 is implanted prior to implantation of tibial tray 1170.In another embodiment, tibial tray 1170 is implanted prior toimplantation of keel 1174. In this embodiment, openings 1178 are sizedso that once tibial tray 1170 is sitting on the tibial surface, keel1174 can be pushed or pounded through opening 1178 to secure tibial tray1170 to tibia 1156.

Base 1172 and keel 1174 can be provided with a locking mechanism tosecure keel 1174 to base 1172. One example of such a mechanism is alocking screw 1181 that inserts through base 1172 and keel 1174. If keel1174 is implanted after tibial tray 1170, keel 1174 can also be providedwith a head 1182 or other stop mechanism that prevents further insertionof keel 1174 through openings 1178 once keel 1174 has been insertedthrough openings 1178 a given distance. In one embodiment, head 1182 canbe made to be flush with superior surface 1180 of base 1172. In thisregard, openings 1178 have a countersink 1184 for accommodating keelhead 1182. In another embodiment, head 1182 extends above superiorsurface 1180 even after full insertion through openings 1178 (i.e.stands proud with respect to superior surface 1180). In this embodiment,keel head 1182 can cooperate with a bore or slit provided on theinferior surface of a tibial insert to serve as a centering mechanismfor insertion (locking the tibial insert to base 1172 in a fixed bearingdesign) and/or articulation of the femoral and tibial components (in amobile bearing design).

If tibial tray 1170 were an integral single-piece unit, it would bedifficult to insert tibial tray 1170 through a minimal incision,regardless of the location of the incision. However, since tibial tray1170 is modular, base 1172 can be readily slid in through either alateral or medial side incision (which can be smaller than typicalmid-line incisions) and, keel 1174 can be interoperatively coupled tobase 1172 after base 1172 is in the desired position. Keel 1174 can beinserted through the same incision as base 1172 or through a separateincision. This separate incision can be a substantially anteriorincision or an incision located on the same or opposite side as theincision for base 1172. As is well known, tibial tray 1170 can beinserted either with or without bone cement. If bone cement is used, thecement can be placed under base 1172 after it is positioned on tibia1156 and then keel 1174 is inserted into openings 1178.

FIG. 80 shows another embodiment of a tibial tray 1186 that can be usedwith or without a keel. An inferior surface 1188 of tibial tray 1186includes a slot 1190 extending substantially across the entire width ofinferior surface 1188. Slot 1190 provides stability for tray 1186. Liketray 1170, tray 1186 can be inserted from either the medial or lateralside. Slot 1190 and/or tibial tray 1186 can be provided with a bore 1192(or a plurality of bores) for receiving a screw 1194 or other fastenerto further secure tray 1186 to the tibia.

Tibial tray 1186 also includes another feature to assist implantation.Specifically, like prior art tibial trays, tibial tray 1186 includes arim 1191 for retaining the tibial insert or bearing surface. However, asshown, rim 1191 does not extend around the entire perimeter of tibialtray 1186. Specifically, lateral and medial posterior regions 1193 haveno rim. A centrally located section 1195 can be provided with a rim forretention of the tibial insert. The elimination of rim 1191 fromposterior regions 1193, facilitates implantation of the femoralcomponent as there is no posterior rim in lateral an medial regions 1193to impede impaction of the femoral component. Section 1195 will notinterfere with impaction of the femoral component as the femoralcomponent has a geometry matching the natural condyles of the femur. Thenovel feature of eliminating the posterior rim can be applied todifferent tibial tray designs and is not limited to tibial tray 1186.

In order to facilitate implantation of tray 1186, a side cutting ormilling jig 1196 (FIG. 81) can be provided with a groove 1198 having ashape that mates with slot 1190. Thus, when tibia 1156 is cut or milled,the tibia has a recess corresponding to the shape of slot 1190, therebyallowing tray 1186 to be readily moved into position. It should be notedthat use of a jig having a groove is not necessary for implantation oftray 1186. For example, tray 1186 can be press fit into position, eitherby tapping in tray 1186 in a direction along the longitudinal axis ofslot 1190 or by tapping tray 1186 from the superior direction. It shouldalso be noted that although slot 1190 is shown having a substantiallydove-tail shape, slot 1190 can be made to have any suitable shape thatprovides stability for tray 1186.

FIG. 82 shows another embodiment of a tibial tray 1200 that has a novelkeel design. A keel 1202 extends from an inferior surface 1204 of tibialbase 1206. A superior surface 1208 is generically shown, and, as is wellknown, is configured and dimensioned for receiving an insert (not shown)that articulates against a femoral component (also not shown). Tibialbase 1206 has lateral and medial regions 1210, 1212.

When viewed from the anterior (FIG. 82) or posterior direction, keel1202 extends downward from inferior surface 1204 at an acute angle.alpha. Thus, keel 1202 extends downward toward lateral region 1210 andaway from medial region 1212. This is in contrast to prior art keels,which generally extend substantially perpendicularly and symmetricallyfrom the tibial base. Like prior art keels, keel 1202 can be tapered andcan be inclined either posteriorly or anteriorly when viewed from themedial/lateral direction. Although keel 1202 is shown as connected toinferior surface 1204 centrally located with respect to both lateral andmedial regions 1210, 1212, keel 1202 can be offset with respect toeither lateral or medial regions 1210, 1212.

FIGS. 83 and 84 show examples of surgical approaches for which tibialtray 1200 is particularly useful. Specifically, knee joint space 1214 isaccessed using a lateral approach such as the procedure previouslydescribed in connection with FIGS. 75-77. Since joint space 1214 ishinged or pivoted open from a lateral aspect 1216 about a medial aspect1218, the area of joint space 1214 that is accessible decreases fromlateral aspect 1216 to medial aspect 1218. As a result, it would bedifficult to insert a typical tibial tray since the length of the keel(compared to the working space of medial aspect 1216) would not permitproper implantation.

FIG. 83 shows one method of implanting tibial tray 1200. Because of thesize and geometry of keel 1202, tibial tray 1200 can be inserted intojoint space 1214 at an angle .beta. (defined by the cut surface of tibia1156 and superior surface 1208 of tibial tray 1200). At angle .beta.,lateral region 1210 is at the same height as medial region 1212 so thatwhen tibial tray 1200 is initially inserted, inferior surface 1204 ofmedial region 1212 is in contact (or close to contact) with tibia 1156.Thus, in order to implant tibial tray 1200 in tibia 1156, lateral region1210 is driven in tibia 1156, with essentially rotation about medialregion 1212 occurring.

FIG. 84 shows another method of implanting tibial tray 1200. Here,superior surface 1208 of tibial tray 1200 is substantially parallel tothe cut surface of tibia 1156. As a result, the distal end of keel 1202is substantially perpendicular to the cut surface of tibia 1156. Thisinitial substantially perpendicular relationship facilitates insertionof keel 1202 into tibia 1156. Regardless of the method of implantation,keel 1202 can have a length so that keel 1202 does not penetrate thelateral cortex of tibia 1156 when fully inserted into tibia 1156.

Although tibial trays 1170, 1186, and 1200 are, as the name implies,intended for use in the tibia, the concepts can be applied to the othercomponents in partial or total knee replacement surgeries. For example,FIG. 85 shows a patellar implant 1220 having a slot 1222 that engagesbone. Thus, patellar implant 1220 is analogous to tibial tray 1186.Typically, patellar implants have one or more pegs that must be driveninto bone. This requires substantial working space, so that the patellaneeds to be everted or dislocated. In contrast, patellar implant 1220can be slid into position without evertion and with little or nodislocation. If desired, patellar implant 1220 can be fixed intoposition with bone cement.

FIG. 86 shows a femoral component 1224 that is also analogous to tibialtray 1186. In particular, femoral component 1224 has a pair of spacedcondyle sections 1226 defining curved condyle surfaces 1228. Joiningregion 1230 is anterior located and connects the two condyle sections1226. Instead of having pins for insertion into the femur, femoralcomponent 1224 is provided with a slot 1232 for securing femoralcomponent 1224 to the femur. Since the pins are absent, femoralcomponent 1224 can be slid into position from the lateral or medialside. As an alternative to slot 1232 (or in addition to slot 1232), eachof condyle sections 1226 can be provided with an aperture for receivinga fastener to secure femoral component 1224 to the femur. This designcould be analogous to tibial tray 1170.

In order to facilitate insertion of femoral component 1224 through aminimally invasive lateral or medial incision, femoral component 1224can be made modular. This allows femoral component 1224 to be implantedin sections through an incision that would otherwise be much longerwhich are then coupled in vivo. As shown, femoral component 1224comprises an anterior femoral section 1234, and a posterior femoralsection 1236. However, any desired number of sections could be used.Anterior femoral section 1234 is coupled to posterior femoral section1236.

FIG. 87 shows one manner of coupling the sections. A tongue 1238 locatedon one section (shown as anterior femoral section 1234) mates with agroove 1240 on an adjacent section (shown as posterior femoral section1236). The mating results in substantially smooth condyle surfaces 1228so as to minimize the potential for generation of wear debris.

Self-Centering Mobile Bearing Implant

FIGS. 88 and 89 show one embodiment of a self-centering mobile bearingimplant according to the present invention. An implant 1250, in the formof a prosthetic knee, comprises a femoral component 1252 secured tofemur 1102 and a tibial component 1254 secured to tibia 1156. Femoralcomponent 1252 includes a pair of spaced apart condyle sections 1256defining curved condyle surfaces 1258. A joining region 1260 is anteriorlocated and connects the two condyle sections 1256 so that a recess 1262is defined by condyle sections 1256 and joining region 1260. The side offemoral component 1252 facing femur 1102 can include fixation pins 1264.As femoral component 1252 has a structure and function analogous toprior art femoral components, further description is not believednecessary.

Tibial component 1254 includes a tray 1266 and a bearing insert 1268.Tray 1266 is defined by a tapered keel or spike 1270 and a plate member1272. As previously discussed with respect to other embodiments, othermechanisms for fixing tibial component 1254 can be used as analternative to spike 1270. Plate member 1272 has a superior surface 1274defined by a concave, spherically shaped plateau surface.

As is more fully described below, bearing insert 1268 also has aspherically shaped surface so that the interface between tibial tray1266 and bearing insert 1268 is defined by cooperating sphericallyshaped, concave and convex surfaces that enable sliding motions alongthese surfaces. In this regard, superior surface 1274 has a mirrorpolish to minimize friction during relative slidable movements ofbearing insert 1268. Additionally, superior surface 1274 is providedwith a track 1276 that cooperates with a groove located on bearinginsert 1268 so that the sliding motion occurs substantially in theanterior-posterior direction. Although a single track 1276 is showncentrally located, track 1276 can be located elsewhere along superiorsurface 1274 and/or more than one track can be used (e.g. two lateralsymmetrically placed tracks). Also, the arrangement of the track andgroove can be switched so that bearing insert 1268 is provided with thetrack and superior surface 1274 is provided with the groove.

Bearing insert 1268 has a superior surface 1278 that includes a pair ofspaced apart curved depressions 1280 that form bearing surfaces forcondyle surfaces 1258 of femoral component 1252. Condyle surfaces 1258and depressions 1280 are shaped so that pivoting motion between femoralcomponent 1252 and bearing insert 1268 can occur over a wide range ofmotion. A protrusion 1282 can be located between depressions 1280 sothat extension of protrusion 1282 into recess 1262 of femoral component1252 substantially prevents hyperextension (counterclockwise rotationbeyond a certain point) of femoral component 1252. Interference betweenprotrusion 1282 and recess 1262 also prevents relative motion in thelateral-medial direction.

Bearing insert 1268 has an inferior surface 1284 that is convex andspherically shaped and mates with concave superior surface 1274 oftibial tray 1266. A groove 1286 is located on inferior surface 1284 andis configured and dimensioned to receive track 1276.

As is evident from the foregoing, implant 1250 operates like prior artmobile bearing knee implants in the occurrence of sliding motion betweenbearing insert 1268 and both femoral and tibial tray 1266 components1252. However, unlike prior art mobile bearing knee implants that relyon tracks and grooves to substantially limit the movement to theanterior-posterior direction, the articulating surfaces are not flat.Rather, superior surface 1274 of tibial tray 1266 and inferior surface1284 of bearing insert 1268 are mating curved surfaces.

With the prior art flat surfaces, there is increased risk fordislocation and variable degrees of laxity. Additionally, ligamentbalancing and self-centering of the joint may be more difficult,allowing for some feelings of instability and/or ligamentous laxity.Because superior surface 1274 of tibial tray 1266 and inferior surface1284 of bearing insert 1268 are mating curved surfaces, the curvaturetoward the center of the tibia encourages bearing insert 1268 to want tofall back into the center of the curvature of superior surface 1274.

In order to enhance ligament stability, tray 1266 and/or bearing insert1268 can be made to have a thickness that increases from the centertoward the edge. As shown in FIGS. 88 and 89, this increase in thicknesscan occur in both the anterior-posterior direction and themedial-lateral direction. Thus, as bearing insert 1268 slides, both thecurvature and decrease in thickness cooperate as a self-centeringmechanism that draws bearing insert 1268 back to the center of the tibia(also resisting posterior rollback), the lowest point in tibial tray1266 when they are at rest. This enhances stability, yet allows freemotion and a mobile bearing construct.

The curvature of inferior surface 1284 of bearing insert 1268 can bemade to match the curvature of superior surface 1274 of tibial tray1266. Alternatively, the curvatures can be different. For example, thecurvature of inferior surface 1284 can be smaller than the curvature ofsuperior surface 1274. Regardless of whether of curvatures match, thecurvature of inferior surface 1284 and/or superior surface 1274 can beconstant or have a radius which progressively varies.

Each of femoral component 1252, tibial tray 1266, and bearing insert1268 can be made of any suitable biocompatible material. For example,femoral component 1252 and tibial tray 1266 can both be made of ametallic material such as a cobalt-chromium alloy or titanium alloy, andbearing insert 1268 can be made of a polymer such as UHMW polyethylene.This provides metal articulating against a polymer. Additionally and aspreviously discussed with respect to other embodiments, this can bereversed so that femoral component 1252 and tibial tray 1266 are made ofa polymer and bearing insert 1268 is made of a metallic material.

FIG. 90 shows another embodiment of the self-centering mechanismaccording to the present invention. An implant 1290 in the form of arotating platform knee implant includes a tibial component 1292 securedto the tibia and a femoral component secured to the femur. As thefemoral component used with implant 1290 is analogous to femoralcomponent 1252, reference is made to FIGS. 88 and 89 and accompanyingtext and further description is not believed necessary.

Tibial component 1292 includes a tray 1294 and a bearing insert 1296.Tray 1294 includes a tapered spike 1298 and a plate member 1300. As wasthe case for tibial component 1254, other mechanisms for fixing tibialcomponent 1292 can be used as an alternative to spike 1298. Plate member1300 has a superior surface 1302 defined by a concave, sphericallyshaped plateau surface.

Analogous to bearing insert 1268, bearing insert 1296 also has aspherically shaped inferior surface 1304 so that the interface betweentibial tray 1294 and bearing insert 1296 is defined by cooperatingspherically shaped, concave and convex surfaces that enable slidingmotions along these surfaces. In this regard, superior surface 1302 hasa mirror polish to minimize friction during relative slidable movementsof bearing insert 1296. Additionally, superior surface 1302 is providedwith a post 1306 that cooperates with a recess 1308 located on bearinginsert 1296 to permit rotation of bearing insert 1296 with respect totibial tray 1294. The arrangement of the post and recess can be switchedso that bearing insert 1296 is provided with the post and superiorsurface 1302 is provided with the recess.

As is evident from the foregoing, implant 1290 operates like prior artmobile bearing knee implants in the occurrence of rotation motionbetween bearing insert 1296 and both femoral and tibial tray components1292. However, unlike prior art mobile bearing knee implants that relyon a post mechanism to control the rotational movement, the articulatingsurfaces are not flat. Rather, superior surface 1302 of tibial tray 1294and inferior surface 1304 of bearing insert 1296 are mating curvedsurfaces.

Compared to the prior art, implant 1290, like implant 1250, providesimproved dislocation risk, ligament balancing, and ligament stability.In order to enhance ligament stability, tray 1294 and/or bearing insert1296 can be made to have a thickness that increases from the centertoward the edge. Thus, as bearing insert 1296 slides, both the curvatureand decrease in thickness cooperate as a self-centering mechanism thatdraws bearing insert 1296 back to the center of post 1306 (alsoresisting posterior rollback), the lowest point in tibial tray 1294 whenthey are at rest. This enhances stability, yet allows free motion and amobile bearing construct.

As is evident from FIG. 90, post 1306 is not located directly over spike1298, i.e. the center of the tibia. Rather, post 1306 is offset mediallytoward the medial compartment of the knee. In prior art rotatingplatform designs, the post is substantially in line with the centralkeel. This design does not account for the anatomical motion of theknee, which has more motion and a greater range of motion laterally withgreater anteroposterior translation laterally and less anteroposteriortranslation medially. Offsetting post 1306 more toward the medialcompartment of the knee recreates the natural pivoting motion on theknee, with less translation medially, a more stable joint medially, andmore rotational arc or more movement laterally.

Any of the above-described embodiments of self-centering mechanism canbe applied to total or partial knee replacement. These embodiments couldbe used in any joint, such as the shoulder, ankle, wrist, as well asothers.

Bicompartment Implants

As previously discussed (see, e.g. FIG. 40 and associated text), thepresent invention includes implants that have interconnectable portions.Another embodiment of this concept is the combination of limitedincision unicompartmental knee replacement with limited incisionpatellofemoral replacement. This combination can be done percutaneouslywith limited incisions, possibly one or two smaller incisions toapproach the medial aspect of the knee in the patellofemoral joint.

Arthritis typically does not involve the entire joint space. Mostarthritis of the knee is medial joint, lateral joint, patellofemoraljoint, or some combination of two of these three joint compartments.Usually advanced arthritis involves both the medial or lateralcompartment and the patellofemoral joint. Replacement of the medial orlateral compartment through limited incision surgery and thenpatellofemoral replacement through the same incision or another incisionwill lead to faster patient rehabilitation.

Additionally, limited incision replacement of these compartments thatavoided everting the patellofemoral joint and reduced damage of thequadriceps mechanism would further accelerate rehabilitation.

FIG. 91 shows a bicompartment arrangement that includes trochlearimplant 1310 and medial implant 1312. Implants 1310 and 1312 aredimensioned and configured so that bone 1314 is located between theimplants. FIG. 92 shows an embodiment of a bicompartment implant 1316that includes trochlear section 1320 and medial section 1322. In implant1316, there is no bone between the sections. Implant 1316 can be made sothat sections 1320 and 1322 are integral. Alternatively, implant 1316could be modular, being assembled inside the body or outside of the bodyprior to implantation.

In the interest of brevity, the reader is referred to FIG. 40 andassociated text for different methods for coupling sections 1320 and1322. As previously discussed, the patella and the other portions of thejoint can be resurfaced to receive the implant. In this regard, theresurfacing can be with a mill, saw or robotic arm and computernavigation system. The computer navigation system could also be used toassist in aligning the unicompartmental replacement with thepatellofemoral joint replacement. The patellofemoral replacement couldbe performed from a mid-vastus or sub-vastus approach without disruptingthe quadriceps mechanism. As also previously discussed, the patellacould be elevated using fluid retractors or simple mechanical retractorsto minimize soft tissue damage associated with dislocating or evertingthe patella.

FIG. 92 shows the tibial component 1324, which articulates againstmedial section 1322. Each of the components can be made of any suitablebiocompatible material. For example, all of the components can be madeof a metallic material such as a cobalt-chromium alloy or titaniumalloy. This provides metal articulating against metal. Alternativearticulating surface pairs include metal/polymer, metal/ceramic,metal/composite, polymer/ceramic, polymer/polymer, polymer/composite,ceramic/ceramic, and ceramic/composite.

In order to reduce the generation of wear debris, the articulatingsurfaces can be magnetically charged to have the same polarity so thatthe surfaces are repelled from each other. Thus, the surfaces glidesmoothly over each other, essentially floating with respect to oneanother. This would also potentially allow a replacement surface that isa strip or point contact, rather than being a full surface that matchesthe surface of the joint. This embodiment, which is described in moredetail below, would include strips that glide along each other, asopposed to a full resurfacing of the joint so one would have strips incontact with each other rather than a full surface. The surface magneticcharges can diminish with time. Additionally, certain environments couldalso diminish the magnetic charges. For example, exposure to an MRIapparatus could severely alter the magnetic fields. In order to accountfor these possibilities, the magnetic charges of the articulatingsurfaces can be re-magnetized.

The present invention also envisions the application of magneticallycharged articulating surfaces to other implant designs and to otherlocations in the body. Examples include the knee, the shoulder (both theglenoid and humeral components), the joints of the hand and wrist, thejoints of the foot and ankle, and the spine. With respect to the spine,suitable procedures include any procedure involving the disc spaceand/or the vertebra.

Adjustable Cutting Jig

As previously discussed, various embodiments of the present inventioninvolve a lateral or medial approach to accessing a joint space. FIG. 93shows an adjustable cutting jig 1330 that is particularly useful in suchan approach. With the cutting jig 1330, the femoral cuts can be made bymoving a saw blade or other cutting device, such as a miller, betweenopposite sides of the femur in a direction extending generallyperpendicular to a longitudinal central axis of the femur. Thus, thecutting device is moved along a path which extends between lateral andmedial surfaces on the distal end portion 1332 of the femur 1334.

The cutting jig 1330 is illustrated in FIG. 93 as being used on alateral surface 1336 of the femur 1334. However, the cutting jig 1330could be used on the medial surface of the femur 1334 if desired. Whenthe cutting jig 1330 is mounted on the lateral surface 1336 of the femur1334, the incision 114 (FIG. 6) is laterally offset. Similarly, when thecutting jig 1330 is mounted on a medial surface of the femur 1334, theincision 114 is medially offset.

Although either intramedullary or extramedullary instrumentation can beused to attach the cutting jig 1330 to the femur 1334, FIG. 93 showsintramedullary instrumentation. Accordingly, the cutting jig 1330includes a shaft 1338 that can be inserted into the medullary canal offemur 1334 in any known manner, for example using a technique analogousto that previously described in connection with FIGS. 8-10. In thisregard, a separate stab wound incision can be made for shaft 1338,rather than attempting to stretch the incision 114.

A length adjustment member 1340 slides along shaft 1338 so that thelocation of length adjustment member 1340 on shaft 1338 can be changedto accommodate different anatomies. Tightening knob 1342 can be used tolock length adjustment member 1340 at the desired location. Lengthadjustment member 1340 can also freely rotate about shaft axis 1344.This is useful, for example, if a medial approach is to be used.

An arm 1346 extends from length adjustment member 1340. Arm 1346includes a head 1348 that is received in ring 1350 on length adjustmentmember 1340. The arm 1346 can be made as two telescoping rods or asimilar configuration so that the length of the arm 1346 can beadjusted. The head 1348 can rotate within the ring 1350 to allowrotation of the arm 1346. A tightening knob 1352 locks the arm 1346 atthe desired position.

An extension 1354 extends from the lateral end of arm 1346. Like the arm1346, extension 1354 can be made as two telescoping rods or a similarconfiguration so that the length of the extension 1354 can be adjusted.A link 1356 is generically shown to indicate that different types ofjoints can be used to couple the arm 1346 and the extension 1354. Forexample, it may be desirable to have the extension 1354 rotate and/orpivot with respect to the arm 1346. Regardless of the specific design ofthe link 1356, a tightening knob 1358 is provided to lock the extension1354 at the desired position.

A cutting guide 1360 is located on an end of the extension 1354. As wasthe case for link 1356, different types of joints can be used to couplethe cutting guide 1360 to the extension 1354. The cutting guide 1360includes a distal guide surface 1362, an anterior chamfer guide surface1364, a posterior chamfer guide surface 1366, an anterior guide surface1368, and a posterior guide surface 1370. As is readily apparent, thecutting guide 1360 has a structure substantially similar to the cuttingguide 800. Furthermore, the operation and use of the cutting guide 1360is substantially similar to that of the cutting guide 800. Accordingly,reference is made thereto.

Each of the guide surfaces 1362, 1364, 1366, 1368, and 1370 can be madeto have a length less than the extent of the cut to be formed on thedistal end portion 1332 of the femur 1334. Therefore, after an initialportion of the cut has been made utilizing the appropriate guide surfaceto guide movement of the cutting tool, the cut surfaces are utilized toguide movement of the cutting tool during completion of the cut. Thecutting guide 1360 is not of the capture type. Therefore, the cuttingtool is free to move past the guide surfaces 1362, 1364, 1366, 1368, and1370 during completion of the femoral cuts. If the guide surfaces 1362,1364, 1366, 1368, and 1370 were formed by slots, the cutting guide 1360could be disconnected from the femur 1334 to complete the femoral cuts.

The cutting guide 1360 can be made so that one or more of the guidesurfaces 1362, 1364, 1366, 1368, and 1370 have an adjustable length sothat the size of the guided portion of the cuts can be adjusteddepending upon the size of the bone and the implant that is to be used.Furthermore, the cutting guide 1360 is shown having a plurality of guidesurfaces 1362, 1364, 1366, 1368, and 1370, with each guide surface beingused to make a different cut. Other embodiments of cutting guides 1360can be used with the cutting jig 1330.

For example, FIG. 94 shows a cutting guide 1372 that has a single guidesurface 1374. As will be discussed, the guide surface 1374 is movable tomake multiple guided cuts of different orientations. As the cuttingguide 1372 only has one guide surface 1374, the cutting guide 1372 canbe used through a smaller incision than prior art cutting blocks. Thecutting guide 1372 includes a base 1376 that can be positioned on thefemur using the adjustable cutting jig 1330. In other words, the cuttingguide 1372 would be a substitute for the cutting guide 1360. Otherintramedullary instrument could be used with the cutting guide 1372.Additionally, extramedullary instrument could be employed. If desired,the base 1376 could be pinned directly to the femur in a manneranalogous to the cutting guide 800 (FIG. 54). Alternatively, the base1376 could be positioned on the femur using a computer navigationsystem.

The base 1376 has a plurality of tracks 1378, 1380, 1382, 1384, and1386. The guide surface 1374 is attached to a pin member 1388. The pinmember 1388 is sized to be received in the tracks 1378, 1380, 1382,1384, and 1386. When pin member 1388 is located in the track 1378, theguide surface 1374 is positioned on the femur for making an anteriorcut, as shown in FIG. 94. When pin member 1388 is located in the track1380, the guide surface 1374 is positioned on the femur for making ananterior chamfer cut, as shown in FIG. 95. When pin member 1388 islocated in the track 1382, the guide surface 1374 is positioned on thefemur for making a distal cut. When pin member 1388 is located in thetrack 1384, the guide surface 1374 is positioned on the femur for makinga posterior chamfer cut. When pin member 1388 is located in the track1386, the guide surface 1374 is positioned on the femur for making aposterior cut.

The pin member 1388 can be locked in the tracks 1378, 1380, 1382, 1384,and 1386 to stabilize the guide surface 1374 during making of the cuts.This can be done in any number of ways. For example, the pin member 1388can have a threaded portion that receives a nut to secure the pin member1388 within the track. The specific configuration of the tracks 1378,1380, 1382, 1384, and 1386 shown in FIGS. 94 and 95 are exemplary only,as any configuration that allows movement of the guide surface 1374 withrespect to the base 1376 could be used.

As was the case with the cutting guide 1360, the guide surface 1374 canbe made so that the size of the guided portion of the cuts can beadjusted depending upon the size of the bone and the implant that is tobe used. Furthermore, the guide surface 1374 can be made to have alength less than the extent of the cut to be formed on the distal endportion of the femur. Therefore, after initial portions of the cuts havebeen made utilizing the guide surface 1374 to guide movement of thecutting tool, the cut surfaces are utilized to guide movement of thecutting tool during completion of the cut. The cutting guide 1372 is notof the capture type. Therefore, the cutting tool is free to move pastthe guide surface 1374 during completion of the femoral cuts. If theguide surface 1374 were of the capture type (having a slot), the cuttingguide 1372 could be disconnected from the femur to complete the femoralcuts.

The cutting guide 1372 is illustrated in FIGS. 94 and 95 for use on alateral surface of the femur. However, the cutting guide 1372 could beused on the medial surface of the femur by either flipping or rotatingthe base 1376. In this regard, FIG. 96 shows a cutting guide 1390 thatcould be used on either the lateral or medial side of the femur. Inaddition to containing the tracks 1378, 1380, 1382, 1384, and 1386, abase 1392 includes tracks 1394, 1396, and 1398. As shown, the track 1396would be used to make a distal femoral cut on the medial side of thefemur.

Implants with Reduced Articulating Surfaces

As previously detailed, the present invention relates to methods,implants, and instrumentation for performing surgery through minimallyinvasive procedures. One aspect is the insertion of a partial or totaljoint replacement implant through a minimally invasive incision. Forexample, modular implants that are assembled after insertion in the bodycan typically be more easily inserted through a smaller incision than aunitary implant of the same size or a modular implant that is assembledprior to implantation. Thus, it is advantageous to have smallerimplants, modular or not, in order to reduce the size of the incisionthat is needed for implantation.

Smaller implants will generally have a smaller articulating surfacearea. While prior art prosthetic components provide a low-frictionarticulating surface for the surface of accompanying member, interactionbetween the articulating component and the member can produce weardebris. Such debris may cause adverse local and systemic reactions inthe body. Thus, it is advantageous to minimize the articulating surfacearea of one or both of a joint component.

FIG. 97 shows one embodiment of a joint component implant 1400 that isboth small in size to facilitate implantation through a minimal incisionand has a reduced articulating surface area. Specifically, implant 1400comprises a head 1402 connected to a body 1404. In use, head 1402articulates against the other joint component. In this regard, the othercomponent could be an artificial component or a natural component. Forexample, if implant 1400 were implanted in the acetabulum 1102 as shownin FIG. 98, the other joint component 1403 could be the natural femoralhead or the head of a prosthetic femoral component. Although head 1402is shown as substantially spherical, any shape that provides a smoothbearing surface could be used.

Body 1404 includes a threaded region 1406 for fixing implant 1400 totissue. A joining region 1408 is located between head 1402 and threadedregion 1406. Joining region 1408 is provided with multiple surfaces sothat an inserter or other tool can be used to thread implant 1400 intotissue. By providing an area separate from head 1402 that is used forinsertion, the risk of scratching or otherwise damaging the bearingsurface is reduced.

Threaded region 1406 can be eliminated and other mechanisms forattaching implant 1400 can be used. For example, implant 1400 couldsimply be driven into the tissue. Bone cement or an adhesive could beused to attach implant 1400. Alternatively, body 1404 could have a rivettype means, an expandable portion, or some other known fixation means.

Implant 1400 can be made from any biocompatible material that willundergo articulating movement with a corresponding natural or prostheticmember. For example, the bearing component could be formed from avariety of metals, polymers, ceramics, or composite materials. In theevent that polymers are chosen, a high density polyethylene may be used,although numerous types of polymers may be suitable so long as thematerial provides both strength and a low-friction articulation surfacefor the corresponding joint face. If desired, head 1402 and body 1404can be made of different materials. It may also be advantageous toinclude some type of known tissue in-growth promoting features on atleast a portion of body 1404. Such features include a porous or texturedsurface, a porous body (for example so-called “foam metals”), andosteoinductive or osteoconductive materials or factors.

FIG. 98 shows a number of implants 1400 located in the acetabulum 1102for articulation against femoral head 1403. As shown, implants 1400 canbe implanted through cannula 1104 and can be cannulated so that they canbe inserted over guide wire 1108, without the need to dislocate thejoint or with only slight dislocation. Implants 1400 also present asmall surface area against which femoral component 1403 articulates. Thebearing surface minimizes available surface area of articulation for thecomponent and the production of wear debris. If desired, implants 1400can be used without the need to ream acetabulum 1102, thereby savingbone stock. Alternatively, acetabulum could be partially reamed toensure a surface free of asperities. Because of the overall reduction insize and bearing surface of implants 1400, a larger femoral component1403 can be used without the risk of significant increase of weardebris. The larger femoral component 1403 may enhance joint stability.

Although any number of implants 1400 can be used for a givenapplication, the use of three implants 1400 for acetabulum 1102 may bepreferable as three implants serve as a centering mechanism for femoralcomponent 1403. In this regard, the number and location of implants 1400can be selected to suit a particular application. The size of implants1400, and in particular head 1402, can also be varied. In acetabulum1102, smaller heads 3-6 mm in diameter or larger heads 10-15 mm indiameter may be desirable.

Although FIG. 98 shows implants 1400 used in acetabulum 1102, implants1400 could be used in any joint component including, a glenoid,patellar, femoral, humoral, tibial, ulnar, radial, wrist, and/or anklecomponent for a prosthetic joint assembly.

FIG. 99 shows another embodiment of a reduced articulating surface areaimplant 1410. Implant 1410 has a substantially annular shape with acurved surface 1412. When implanted, surface 1412 serves as the bearingsurface against which the other joint component articulates. Surface1412 can be provided with a beveled bearing surface, if desired. Theannular shape of implant 1410 defines an interior region 1414. Ifimplant 1410 were to be used on the femur, implant 1410 would be placedaround the femoral head with interior region 1414 in contact with bone.If implant 1410 were to be used on the acetabulum, implant 1410 could befixed to the bone or freely float within the acetabulum with nofixation. As was the case for implant 1400, implant 1410 can be used inother joints.

FIG. 100 shows another embodiment of a reduced articulating surface areaimplant 1416. Like implant 1410, implant 1416 is a unitary implant thatcan be implanted through a minimal incision, has a reduced articulatingsurface area, and does not require extensive removal of bone. Ratherthan having a ring shape, implant 1410 has a U-shaped body with curvedsurface 1418 that serves as the bearing surface.

Disposable Trial Implants, Instruments, and Other Surgical Implements

As previously discussed throughout this specification, the presentinvention includes disposable surgical implants and instruments.Currently for hip, knee, shoulder, and other joint replacement surgeries(partial or total), there can be six or more trays of instruments andtrial implants. Each tray has to be re-sterilized for each procedure. Inthe case of knee replacement surgeries, one tray may contain femoraltrials, one may contain tibial trials, one may contain polyethylenespacer blocks, one may contain tibial cutting instruments, and one traymay contain femoral cutting instruments.

This is cumbersome and unnecessary as only a few of these instrumentsand trial implants need to be made of surgical grade metal and alloysthat are rigid and reusable. There is a significant expense in themultiple tray setups. One company, for example, spends over $150 millionjust to have instruments in the field. Additionally, shipping chargesand re-sterilization costs can be significant. The delay due to theshipping and re-sterilization also adds hidden costs and time.Obviously, money and time can be saved if the number of trays for eachprocedure were reduced.

Also, as a company modifies implant systems or instruments,representatives of the company need to update their inventoriesaccordingly. Frequently, companies are unable to charge for the newinstruments as an incentive to promote a new system. Although thesecosts cannot be recovered, they ultimately add to the cost of jointreplacement surgeries.

These issues can be addressed by a disposable trialing system. Forexample, the tibial trial base plate 270 (FIG. 26) and other trialcomponents can be made of a light-weight low cost material such asaluminum, injection molded plastic, composite material, and the like.There would be a series of these disposable trial implants in varioussizes for the implant system the surgeon intended to use. Each wouldcome pre-packaged in a sterile state. Alternatively, each sterilepackage could include different components of the same size. In the caseof a knee replacement procedure, each sterile package could include afemoral trial, a tibial trial, a patellar trial, and a spacer trial.Preoperatively, the surgeon could obtain an estimate of the needed sizefrom x-rays and other clinical information. Based upon this estimate,one or more sizes of the trial implants would be brought to theoperating room or surgical suite.

The use of disposable trial implants would reduce the number of traysneeded for a given procedure. The use of disposable cutting blocks wouldfurther reduce the number of trays. In this regard, the disposablecutting blocks could be made of a material that has color or some otherchemical or physical property that would allow the detection of traceamounts of the cutting blocks. This is particularly useful if thecutting blocks are inadvertently scratched so that any debris could bedetected and removed. The instruments and trials could have changeablelugs, changeable stems, or similar modularity to allow modification ofthe position and the rotation.

If desired, some or all of the instruments and other disposables couldbe packaged in a single sterile unit. Some items that could be includedin the unit include the instruments, draping, cement, cement mixer,pulsatile lavage, retractors, drill bits, pins, and guide wires. Thiswould save significant time for the operating personnel as they openthis unit and it has all the cutting blocks.

One advantage of the disposable system is that the disposable cuttingblocks could easily be modified for new or updated instrumentation orfor customized instrumentation. The disposable system saves the cost andtime of cleaning and re-sterilization. Also, the disposable system wouldimprove the sterile technique in the operating room and since these aresingle use and sterilized there is no risk of cross-contamination goingfrom one patient to another patient.

If desired, only a portion of the trial implants or instrumentationcould be disposable. For example, the intramedullary rod for distalfemoral cutting blocks could be reusable, however, the actual cuttingsurface, such as the captured guide 4 in 1 block, the mill cut, etc.,could be disposable.

Program for Learning Minimally Invasive Surgical Techniques

As the minimally invasive surgical instruments, implants, systems, andmethods disclosed herein represent a significant deviation from thoseused in open surgical procedures, the present invention includes aprogram for training surgeons and other health care professionals. Theprogram is a sequential approach in which the trainee starts thetraining process using an incision of standard length and progressivelydecreases the incision size as milestones are achieved.

The program is sequential learning, analogous to returning to residencyor a mini-fellowship. The program can involve a series of visits to adedicated training sites and/or remote linking, for example viavideoconferences or the Internet, to certain training programs. The goalof the program is to allow the trainee to progress from: working with astandard incision, traditionally to learn anatomy; working through asmaller incision, with a combination of prior art instruments andimplants and the downsized instruments and implants according to thepresent invention; and working through a minimally invasive incision touse the instruments, implants, systems, and techniques according to thepresent invention. As previously discussed, these techniques includeminimizing or avoiding joint dislocation, video and fluoroscopic orother radiographic guidance, computer assisted surgical procedures,cannulated instruments and implants, and downsized instruments andimplants.

The program can include the following training tools, in anycombination: lectures and video demonstrations to understand theinstruments, both intra and extramedullary, implants, systems, andmethods; observation and discussion of live broadcast surgeries;practice using saw bones; practice with cadavers, animal models, orplastic models that have artificial skin, muscle, tissue, ligaments, andbones; virtual reality evaluations; and practice with minimal incisions.

Once proficiency with some or all of the training tools have beachieved, which can be determined by grading based on examination, thetrainee can be assigned a mentor, a previously certified health careprofessional. The trainee can be required to visit and observe thementor during surgery. Additionally, the mentor could visit the traineeat the trainee's practice and supervise or otherwise monitor thetrainee's techniques.

Even after the initial visits between the mentor and trainee, the mentorcould be available for consultation by the trainee. The trainee couldstart probationary work at his practice by initially using an incisionthat is only slightly smaller than standard incisions. The x-rays,inter-operative pictures or videos, and other case data could bereviewed and graded by the mentor or other certified instructor.Advancement to the next level would only be allowed if the review weresatisfactory. The next level could involve a return to some or all ofthe training tools to practice working through a smaller incision, witha combination of prior art instruments and implants and the downsizedinstruments and implants according to the present invention. After thetraining tools are mastered, probationary work by the trainee at thislevel would be followed by review and grading by the mentor or othercertified instructor. Once again, advancement to the next level wouldonly be allowed if the review were satisfactory. The process is repeatedfor the final level.

The program could be implemented so that the trainee must meet givenstandards in order to receive instrumentation and implants to allow thetrainee to perform the procedures independently without supervision.Furthermore, achieving these standards could be required prior to beingallowed to promote or advertise proficiency in the techniques. Thestandards could be coordinated with hospital Institutional ReviewBoards.

The program could be offered through a professional society, such as theAmerican Academy of Orthopaedic Surgeons and the Hip and Knee Society, acommercial entity, or some combination thereof. Continuing MedicalEducation (CME) credits and grades could be provided. The instructorsand preceptors could be certified, with the certification processthrough a professional society.

The trainees could pay a portion of the costs of the program. Traineeswould offset the costs of the program from the added revenue from theprocedures and possible lower insurance premiums. The costs of theprogram may be subsidized by governmental agencies and commercialentities, which would benefit from sales and leasing of instruments andimplants. Costs could be subsidized by insurers, which would benefitfrom the lower costs of the procedures compared to traditional openprocedures. Finally, costs could also be subsidized by surgical centers,which would benefit from having trained personnel and added revenue fromthe procedures.

In additional to the educational benefits of the program, the programalso provides some legal protection to the trainees. Perhaps moreimportantly, the program affords protection to the patient by ensuringadequately trained medical personnel.

CONCLUSION

In view of the foregoing description, it is apparent that the presentinvention relates to a new and improved method and apparatus for use inperforming any desired type of surgery on a joint in a patient's body.The joint may advantageously be a joint in a knee portion 76 of apatient's leg 70. However, the method and apparatus may be used inassociation with surgery on other joints in a patient's body. There aremany different features of the present invention which may used eithertogether or separately in association with many different types ofsurgery. Although features of the present invention may be used withmany different surgical procedures, the invention is described herein inconjunction with surgery on a joint in a patient's body.

One of the features of the present invention relates to the making of alimited incision 114. The limited incision 114 may be in any desiredportion of a patient's body. For example, the limited incision 114 maybe in a knee portion 76 of a leg 70 of a patient. The limited incision114 may be made while a lower portion 68 of the leg 70 of the patient isextending downward from the upper portion 72 of the leg of the patient.At this time, a foot 74 connected with the lower portion 68 of the legof the patient may be below a surface 64 on which the patient issupported. The limited incision 114 may be made while the lower portion68 of the leg 70 of the patient is suspended from the upper portion ofthe leg or while the lower portion of the leg and/or the foot 74 of thepatient are held by a support device. After the incision 114 has beenmade, any one of many surgical procedures may be undertaken.

It is believed that in certain circumstances, it may be desired to havea main incision 114 of limited length and a secondary incision 920 ofeven smaller length. The secondary incision 920 may be a portal or stabwound. A cutting tool 170 may be moved through the secondary incision920. An implant 286, 290 and/or 294 may be moved through the mainincision 114.

Once the incision 114 has been made, a patella 120 in the knee portion76 of the patient may be offset to one side of its normal position. Whenthe patella 120 is offset, an inner side 122 of the patella faces inwardtoward the end portions 124 and 212 of a femur 126 and tibia 214.

Although any one of many known surgical procedures may be undertakenthrough the limited incision 114, down sized instrumentation 134, 138,186, 210 and/or 218 for use in the making of cuts in a femur 126 and/ortibia 214 may be moved through or part way through the incision. Thedown sized instrumentation may be smaller than implants 286, 290 and/or294 to be positioned in the knee portion 76 of the patient. The downsized instrumentation 286, 290 and/or 294 may have opposite ends whichare spaced apart by a distance which is less than the distance betweenlateral and medial epicondyles on a femur or tibia in the leg of thepatient.

It is contemplated that the down sized instrumentation 134, 138, 186,210 and/or 218 may have cutting tool guide surfaces of reduced length.The length of the cutting tool guide surfaces may be less than thelength of a cut to be made on a bone. A cut on a bone in the patient maybe completed using previously cut surfaces as a guide for the cuttingtool.

It is contemplated that at least some, if not all, cuts on a bone may bemade using light directed onto the bone as a guide. The light directedonto the bone may be in the form of a three dimensional image 850. Thelight directed onto the bone may be a beam 866 or 868 along which acutting tool 170 is moved into engagement with the bone.

There are several different orders in which cuts may be made on bones inthe knee portion of the leg of the patient. It is believed that it maybe advantageous to make the patellar and tibial cuts before making thefemoral cuts.

There are many different reasons to check ligament balancing in a kneeportion 76 of the leg of a patient. Ligament balancing may be checkedwhile the knee portion 76 of the leg 70 of the patient is flexed and thefoot 74 of the patient is below the support surface 64 on which thepatient is disposed. Flexion and extension balancing of ligaments may bechecked by varying the extent of flexion of the knee portion 76 of theleg 70 of the patient. In addition, rotational stability of theligaments may be checked by rotating the lower portion of the leg of thepatient about its central axis. Balancing of ligaments may also bechecked by moving the foot 74 of the patient sideways, rotating thelower portion 68 of the leg 70 of the patient, and/or moving the footanteriorly or posteriorly.

It is believed that it may be advantageous to utilize an endoscope 352or a similar apparatus to examine portions of the patient's body whichare spaced from the incision 114. It is also contemplated that images ofthe knee portion of the patient's leg may be obtained by using any oneof many known image generating devices other than an endoscope 352. Theimages may be obtained while the patient's leg 70 is stationary or inmotion. The images may be obtained to assist a surgeon in conducting anydesired type of surgery.

Balancing of the ligaments in the knee portion 76 of a patient's leg 70may be facilitated by the positioning of one or more transducers 596and/or 598 between tendons, ligaments, and/or bones in the knee portion.One transducer 598 may be positioned relative to a medial side of a kneejoint. Another transducer 596 may be positioned relative to a lateralside of the knee joint. During bending of the knee joint, the outputfrom the transducers 596 and 598 will vary as a function of variationsin tension forces in the ligaments. This enables the tension forces inligaments in opposite sides of the knee portion to be compared tofacilitate balancing of the ligaments.

Patellar tracking may be checked by the positioning of one or moretransducers 930 and/or 932 between the patella 120 and the distal endportion 124 of the femur 126. If desired, one transducer 932 may beplaced between a medial portion of the patella 120 and the distal endportion 124 of the femur 126. A second transducer 930 may be placedbetween a lateral portion of the patella 120 and the distal end portion124 of the femur 126. Output signals from a transducer 930 will vary asa function of variations in force transmitted between the patella 120and femur 126 during bending of the leg.

The articular surface 122 on the patella 120 may be repaired. Thedefective original articular surface 122 on the patella 120 may beremoved by cutting the patella while an inner side of the patella facestoward a distal end portion 124 of a femur 126. The step of cutting thepatella may be performed while the patella is disposed in situ and isurged toward the distal end portion of the femur by connective tissue.An implant may then be positioned on the patella 120.

It is contemplated that the size of the incision 114 in the knee orother portion of the patient may be minimized by conducting surgerythrough a cannula 564. The cannula 564 may be expandable. To facilitatemoving of an implant 286, 290 and/or 294 through the cannula 564, theimplant may be formed in two or more portions 572 and 574. The portionsof the implant 286, 290 and/or 294 may be interconnected when theportions of the implant have been positioned in the patient's body.Although the implants disclosed herein are associated with a patient'sknee, it should be understood that the implants may be positioned at anydesired location in a patient's body.

An implant 626, 640 or 670 may be positioned in a recess 610, 642 or 672formed in a bone 126 or 214 in a patient. The implant 626, 640 or 670may contain biological resurfacing and/or bone growth promotingmaterials. The implant 626, 640 and/or 670 may contain mesenchymal cellsand/or tissue inductive factors. Alternatively, the implant 626 or 640may be formed of one or more materials which do not enable bone to growinto the implant.

In accordance with one of the features of the present invention, bodytissue may be moved or stretched by a device 720, 722 and/or 730 whichis expandable. The expandable device 720, 722 and/or 730 may bebiodegradable so that it can be left in a patient's body. The expandabledevice 720, 722 and/or 730 may be expanded to move and/or stretch bodytissue and increase a range of motion of a joint. The expandable devicemay be used to stretch body tissue in which an incision is to be made.

An improved drape system 100 is provided to maintain a sterile fieldbetween a surgeon 106 and a patient during movement of the surgeonrelative to the patient. The improved drape system 100 includes a drape102 which extends between the surgeon and a drape 90 for the patient.During surgery on a knee portion 76 of a leg 70 of a patient, the drapesystem 100 extends beneath the foot portion 74 of the leg 70 of apatient. It is contemplated that the drape system 100 will be utilizedduring many different types of operations other than surgery on a leg ofa patient.

An implant 950, 970, 980, 1002, 1020, 1040 or 1060 may be movablerelative to both a femur 126 and a tibia 214 in a leg of a patientduring bending of the leg. The implant may include a single member(FIGS. 59, 60, 63, 64 and 65) which is disposed between and engage byend portions of the femur and tibia. Alternatively, the implant mayinclude a plurality of members (FIGS. 61 and 62) which are disposed inengagement with each other. If desired one of the members of theplurality of members may be secured to a bone and engaged by a memberwhich is not secured to a bone. The implant may be secured to softtissue in the knee portion of the patient's leg (FIGS. 63 and 64).

There are many different features to the present invention. It iscontemplated that these features may be used together or separately. Itis also contemplated that the features may be utilized in associationwith joints in a patient's body other than a knee joint. For example,features of the present invention may be used in association withsurgery on vertebral joints or glenoid joints. However, it is believedthat many of the features may be advantageously utilized together duringthe performance of surgery on a patient's knee. However, the inventionshould not be limited to any particular combination of features or tosurgery on any particular joint in a patient's body. It is contemplatedthat features of the present invention will be used in association withsurgery which is not performed on a joint in a patient's body.

Thus, while various descriptions of the present invention are describedabove, it should be understood that the various features can be usedsingly or in any combination thereof. Therefore, this invention is notto be limited to only the specifically preferred embodiments depictedherein. Further, it should be understood that variations andmodifications within the spirit and scope of the invention may occur tothose skilled in the art to which the invention pertains. Accordingly,all expedient modifications readily attainable by one versed in the artfrom the disclosure set forth herein that are within the scope andspirit of the present invention are to be included as furtherembodiments of the present invention. The scope of the present inventionis accordingly defined as set forth in the appended claims.

What is claimed is:
 1. An apparatus for measuring forces in a kneejoint, the apparatus comprising: a first transducer configured to bepositioned in a medial compartment of the knee joint, the firsttransducer being configured to measure a first force in the medialcompartment of the knee and transmit the first force measurement to adisplay; and a second transducer configured to be positioned in alateral compartment of the knee joint, the second transducer beingconfigured to measure a second force in the lateral compartment of theknee and transmit the second force measurement to the display.
 2. Theapparatus of claim 1, wherein the medial and lateral transducer arepiezoelectric load cells.
 3. The apparatus of claim 1, wherein theapparatus is configured to be used in combination with a provisionalimplant component.
 4. The apparatus of claim 1, wherein the apparatus isconfigured to be placed between a femoral implant component and a tibialimplant.
 5. The apparatus of claim 1, further comprising a processorconnected to the first and second transducer.
 6. A method of measuringforces in a knee joint, the method comprising: attaching a femoralimplant to a distal end of a femur; attaching a tibial base plate to aproximal end of a tibia; positioning a first transducer in a medialcompartment of the knee between the femoral implant and the tibial baseplate; positioning a second transducer in a lateral compartment of theknee between the femoral implant and the tibial base plate; flexing andextending the knee joint; measuring the forces in the medial and lateralcompartments of the knee joint; and transmitting the measurements to adisplay.
 7. The method of claim 6, the method further comprisingcorrelating the measured forces to tensions in ligaments of the kneejoint.
 8. The method of claim 7, the method further comprising comparingthe tensions of the ligaments of the knee joints.
 9. The method of claim6, the method further comprising releasing a ligament if the measuredforce is too large.
 10. The method of claim 6, the method furthercomprising tightening a ligament if the measured force is too small. 11.A method of measuring forces in a knee joint, the method comprising:positioning a first transducer in a medial compartment of the kneebetween a femur and a tibia; positioning a second transducer in alateral compartment of the knee between the femur and the tibia; flexingand extending the knee joint; measuring the forces in the medial andlateral compartments of the knee joint; and transmitting themeasurements to a display.
 12. The method of claim 11, the methodfurther comprising correlating the measured forces to tensions inligaments of the knee joint.
 13. The method of claim 12, the methodfurther comprising comparing the tensions of the ligaments of the kneejoints.
 14. The method of claim 11, the method further comprisingreleasing a ligament if the measured force is too large.
 15. The methodof claim 11, the method further comprising tightening a ligament if themeasured force is too small.
 16. The method of claim 11, the methodfurther comprising attaching a femoral implant to a distal end of thefemur.
 17. The method of claim 11, the method further comprisingattaching a tibial implant to a proximal end of the tibia.
 18. A methodof measuring force in a knee joint, the method comprising: positioning atransducer in the knee between a femur and a tibia; flexing andextending the knee joint; measuring the force in the knee joint; andtransmitting the measurement to a display.
 19. The method of claim 18,the method further comprising correlating the measured force to tensionin a ligament of the knee joint.
 20. The method of claim 18, the methodfurther comprising releasing a ligament if the measured force is toolarge.
 21. The method of claim 18, the method further comprisingtightening a ligament if the measured force is too small.
 22. The methodof claim 18, the method further comprising attaching a femoral implantto a distal end of the femur.
 23. The method of claim 18, the methodfurther comprising attaching a tibial implant to a proximal end of thetibia.